Move version functionality to its own `helpers/version.py` file

diff --git a/src/seedsigner/controller.py b/src/seedsigner/controller.py
index 877e348..c2ecf96 100644
--- a/src/seedsigner/controller.py
+++ b/src/seedsigner/controller.py
@@ -23,9 +23,6 @@ from seedsigner.views.view import Destination
 logger = logging.getLogger(__name__)
 
 
-VERSION = "0.8.6"
-
-
 
 class BackStack(list[Destination]):
     def __repr__(self):
@@ -478,70 +475,3 @@ class Controller(Singleton):
             exception_msg,
         ]
         return Destination(UnhandledExceptionView, view_args={"error": error}, clear_history=True)
-
-
-    def get_version(self) -> str:
-        """
-            Will attempt to read the current git branch name or commit hash from
-            .git/HEAD. But if there's no git info available, it will fall back to the
-            hard-coded Controller.VERSION.
-        """
-        name = f"v{VERSION}"
-
-        # .git/HEAD will be in the project root, if it exists
-        git_HEAD_dir = os.getcwd()
-
-        # Main app runs from src/ dir, tests and screenshot generator from project root
-        if "src" in git_HEAD_dir:
-            git_HEAD_dir = os.path.join(git_HEAD_dir, "..")
-        git_HEAD_path = os.path.join(git_HEAD_dir, ".git", "HEAD")
-
-        if os.path.exists(git_HEAD_path):
-            with open(git_HEAD_path, "r") as f:
-                git_ref = f.read().strip()
-                if git_ref.startswith("ref:"):
-                    # HEAD format: "ref: refs/heads/some_branch_name"
-                    name = git_ref.split("/")[-1]
-                else:
-                    # If we're on a detached HEAD, the contents will just be the current
-                    # commit hash.
-                    name = git_ref[:7]
-
-                    # Check the .git/refs/tags dir for a tag matching this commit hash
-                    git_refs_tags_dir = os.path.join(git_HEAD_dir, ".git", "refs", "tags")
-                    if os.path.exists(git_refs_tags_dir):
-                        for tag_filename in os.listdir(git_refs_tags_dir):
-                            tag_path = os.path.join(git_refs_tags_dir, tag_filename)
-                            with open(tag_path, "r") as tag_file:
-                                # Tag files just contain their associated commit hash
-                                tag_commit_hash = tag_file.read().strip()
-                                if tag_commit_hash == git_ref:
-                                    # Filename is the tag name
-                                    name = f"v{tag_filename}"
-                                    break
-
-        return name
-
-
-    def get_last_src_edit(self) -> datetime:
-        """
-        Recursively scan the src/ directory for the most recent python file edit time and
-        return it.
-        """
-        src_path = os.getcwd()
-        if "src" not in src_path:
-            # Screenshot generator runs from the project root
-            src_path = os.path.join(src_path, "src")
-
-        latest_edit = 0
-        for dirpath, dirnames, filenames in os.walk(src_path):
-            if "__pycache__" in dirpath:
-                continue
-            for filename in filenames:
-                if filename.endswith(".py"):
-                    filepath = os.path.join(dirpath, filename)
-                    mtime = os.path.getmtime(filepath)
-                    if mtime > latest_edit:
-                        latest_edit = mtime
-
-        return datetime.fromtimestamp(latest_edit)
\ No newline at end of file
diff --git a/src/seedsigner/gui/screens/settings_screens.py b/src/seedsigner/gui/screens/settings_screens.py
index 14e27d2..2c1ed82 100644
--- a/src/seedsigner/gui/screens/settings_screens.py
+++ b/src/seedsigner/gui/screens/settings_screens.py
@@ -353,12 +353,13 @@ class VersionScreen(BaseTopNavScreen):
             screen_y=screen_y,
         ))
 
-        last_edit_str = self.last_edit.strftime("%Y-%m-%d\n%H:%M:%S UTC")
-        self.components.append(TextArea(
-            text=last_edit_str,
-            is_text_centered=True,
-            screen_y=self.components[-1].screen_y + self.components[-1].height + 2*GUIConstants.COMPONENT_PADDING,
-        ))
+        if self.last_edit:
+            last_edit_str = self.last_edit.strftime("%Y-%m-%d\n%H:%M:%S UTC")
+            self.components.append(TextArea(
+                text=last_edit_str,
+                is_text_centered=True,
+                screen_y=self.components[-1].screen_y + self.components[-1].height + 2*GUIConstants.COMPONENT_PADDING,
+            ))
 
 
 
diff --git a/src/seedsigner/helpers/version.py b/src/seedsigner/helpers/version.py
new file mode 100644
index 0000000..db1d4ab
--- /dev/null
+++ b/src/seedsigner/helpers/version.py
@@ -0,0 +1,129 @@
+import logging
+import os
+from datetime import datetime
+
+
+logger = logging.getLogger(__name__)
+
+
+
+class Version:
+    """
+    Utility class to detect the current version and the last edit time of the source code.
+
+    Version detection attempts to read the current git branch, commit hash, or tag but
+    will fall back to the hard-coded VERSION constant if no git info is available.
+
+    Internal utility functions are separated out as class methods for easier mocking in tests.
+    """
+
+    VERSION = "0.8.6"
+
+
+    @classmethod
+    def _get_dot_git_dir(cls) -> str:
+        # .git will be in the project root, if it exists
+        git_HEAD_dir = os.getcwd()
+
+        # Main app runs from src/ dir, tests and screenshot generator from project root
+        if "src" in git_HEAD_dir:
+            git_HEAD_dir = git_HEAD_dir.rsplit("src", 1)[0]
+
+        return os.path.join(git_HEAD_dir, ".git")
+
+
+    @classmethod
+    def _read_HEAD_file(cls) -> tuple[str,str]:
+        git_HEAD_path = os.path.join(cls._get_dot_git_dir(), "HEAD")
+
+        branch_name = None
+        commit_hash = None
+        if os.path.exists(git_HEAD_path):
+            with open(git_HEAD_path, "r") as f:
+                git_ref = f.read().strip()
+                if git_ref.startswith("ref:"):
+                    # HEAD format: "ref: refs/heads/some_branch_name"
+                    branch_name = git_ref.split("/")[-1]
+                else:
+                    # If we're on a detached HEAD, the contents will just be the current
+                    # commit hash.
+                    commit_hash = git_ref
+        return (branch_name, commit_hash)
+
+
+    @classmethod
+    def _get_matching_tag(cls, commit_hash: str) -> str:
+        # Check the .git/refs/tags dir for a tag matching this commit hash
+        git_refs_tags_dir = os.path.join(cls._get_dot_git_dir(), "refs", "tags")
+        if os.path.exists(git_refs_tags_dir):
+            for tag_filename in os.listdir(git_refs_tags_dir):
+                tag_path = os.path.join(git_refs_tags_dir, tag_filename)
+                with open(tag_path, "r") as tag_file:
+                    # Tag files just contain their associated commit hash
+                    tag_commit_hash = tag_file.read().strip()
+                    if tag_commit_hash == commit_hash:
+                        # Filename is the tag name
+                        return tag_filename
+        return None
+
+
+    @classmethod
+    def get_version(cls) -> str:
+        """
+            Will attempt to read the current git branch name or commit hash from
+            .git/HEAD. But if there's no git info available, it will fall back to the
+            hard-coded VERSION constant.
+        """
+        name = f"v{cls.VERSION}"
+
+        branch_name, commit_hash = cls._read_HEAD_file()
+        if branch_name:
+            name = branch_name
+        elif commit_hash:
+            # See if this commit_hash matches a tag
+            matching_tag = cls._get_matching_tag(commit_hash)
+            if matching_tag:
+                name = matching_tag
+            else:
+                name = commit_hash[:7]  # short commit hash
+
+        return name
+
+
+    @classmethod
+    def get_last_src_edit(cls) -> datetime:
+        """
+        Recursively scan the src/ directory for the most recent python file edit time.
+        """
+        try:
+            src_path = os.getcwd()
+            if "src" not in src_path:
+                # Screenshot generator runs from the project root
+                src_path = os.path.join(src_path, "src")
+
+            last_modified = 0.0
+            num_files = 0
+            for dirpath, dirnames, filenames in os.walk(src_path):
+                if "__pycache__" in dirpath:
+                    continue
+                for filename in filenames:
+                    if filename.endswith(".py"):
+                        num_files += 1
+                        filepath = os.path.join(dirpath, filename)
+
+                        # getmtime 
+                        file_mtime = os.path.getmtime(filepath)
+                        last_modified = max(file_mtime, last_modified)
+
+            # Sanity check
+            if num_files == 0:
+                raise Exception(f"No python source files found in {src_path}")
+
+            return datetime.fromtimestamp(last_modified)
+
+        except Exception as e:
+            # Catch and log any unexpected errors but this isn't a mission-critical
+            # function so return gracefully.
+            import traceback
+            logger.error(traceback.format_exc())
+            return None
\ No newline at end of file
diff --git a/src/seedsigner/views/screensaver.py b/src/seedsigner/views/screensaver.py
index 25be5cc..3160626 100644
--- a/src/seedsigner/views/screensaver.py
+++ b/src/seedsigner/views/screensaver.py
@@ -8,6 +8,7 @@ from gettext import gettext as _
 
 from seedsigner.gui.components import Fonts, GUIConstants, load_image
 from seedsigner.gui.screens.screen import BaseScreen
+from seedsigner.helpers.version import Version
 from seedsigner.models.settings import Settings
 from seedsigner.models.settings_definition import SettingsConstants
 from seedsigner.views.view import View
@@ -97,7 +98,7 @@ class OpeningSplashScreen(LogoScreen):
 
         # Display version num below SeedSigner logo
         font = Fonts.get_font(GUIConstants.get_body_font_name(), GUIConstants.get_top_nav_title_font_size())
-        version = controller.get_version()
+        version = Version.get_version()
 
         # The logo png is 240x240, but the actual logo is 70px tall, vertically centered
         logo_height = 70
diff --git a/src/seedsigner/views/settings_views.py b/src/seedsigner/views/settings_views.py
index a35631d..85b446e 100644
--- a/src/seedsigner/views/settings_views.py
+++ b/src/seedsigner/views/settings_views.py
@@ -328,13 +328,12 @@ class DonateView(View):
 
 class VersionView(View):
     def run(self):
-        from seedsigner.controller import Controller
-        controller = Controller.get_instance()
+        from seedsigner.helpers.version import Version
 
         self.run_screen(
             settings_screens.VersionScreen,
-            version=controller.get_version(),
-            last_edit=controller.get_last_src_edit(),
+            version=Version.get_version(),
+            last_edit=Version.get_last_src_edit(),
         )
 
         return Destination(SettingsMenuView)
\ No newline at end of file