Simplify version.json file write; standardize on matching SeedSigner OS builder output even in local dev

diff --git a/tools/write_versionfile.py b/tools/write_versionfile.py
index 79c4c8b..861e8c9 100644
--- a/tools/write_versionfile.py
+++ b/tools/write_versionfile.py
@@ -1,6 +1,7 @@
 import json
+import os
 
-from seedsigner.helpers.version import VersionUtils
+from seedsigner.helpers.version import Version, VersionUtils
 
 
 """
@@ -21,7 +22,8 @@ Version data:
         * Check for the SEEDSIGNER_VERSION_NAME env var (provided in SeedSigner OS build
           env).
             * Will be the branch, tag, or commit hash being built.
-        * In local dev will fall back to using `git` shell commands:
+        * If running in local dev instead, this script will try to populate that env var
+          using `git` shell commands:
             * Current git branch name
             * Current git tag name
             * Current git commit hash
@@ -32,31 +34,23 @@ Version data:
     * version_timestamp:
         * Pulls last git commit time from `git log`.    
 
-    * version_commit_hash:
+    * short_commit_hash:
         * Pulls current git commit hash from `git` shell command.
 """
-
 if __name__ == "__main__":
-    version_info = dict()
-
-    for get_version_name_method in [
-        VersionUtils._get_version_name_from_seedsigner_os_env_var,
-        VersionUtils._get_version_name_from_git_shell,
-    ]:
-        version_name = get_version_name_method()
-        if version_name:
-            break
+    is_seedsigner_os_builder = VersionUtils._is_seedsigner_os_builder_env()
 
-    version_timestamp = VersionUtils._get_version_timestamp_from_git_shell()
-    version_commit_hash = VersionUtils._get_full_commit_hash_from_git_shell()
+    if not is_seedsigner_os_builder:
+        # Pull version_name from the current git state via `git` shell commands
+        version_name = VersionUtils._get_version_name_from_git_shell()
+        
+        # Temporarily set the env var
+        os.environ[VersionUtils.ENV_VAR__SEEDSIGNER_OS_BUILDER__VERSION_NAME] = version_name
 
-    if not version_name or not version_timestamp or not version_commit_hash:
-        raise Exception("Could not determine version information from git.")
-
-    version_info[VersionUtils.VERSIONFILE_ATTR__NAME] = version_name
-    version_info[VersionUtils.VERSIONFILE_ATTR__FORK] = VersionUtils._get_version_fork_from_git_shell()
-    version_info[VersionUtils.VERSIONFILE_ATTR__TIMESTAMP] = version_timestamp.isoformat()
-    version_info[VersionUtils.VERSIONFILE_ATTR__COMMIT_HASH] = version_commit_hash[:7]  # short hash
+    # When the `Version` singleton instantiates itself, it will determine for itself how to
+    # get the timestamp based on the SeedSigner OS builder env var being set or not.
+    version_instance = Version.get_instance()
+    version_info = version_instance.to_dict()
 
     version_file_path = VersionUtils._get_version_file_path()
     with open(version_file_path, "w") as f:
@@ -64,3 +58,7 @@ if __name__ == "__main__":
 
     print(f"Wrote version info to: {version_file_path}")
     print(json.dumps(version_info, indent=4))
+
+    # Clean up the temp env var if needed
+    if not is_seedsigner_os_builder:
+        del os.environ[VersionUtils.ENV_VAR__SEEDSIGNER_OS_BUILDER__VERSION_NAME]