wallet: refactor: add encrypt_message method, consolidated from UIs

diff --git a/electrum/commands.py b/electrum/commands.py
index f81628f..3f83148 100644
--- a/electrum/commands.py
+++ b/electrum/commands.py
@@ -1226,15 +1226,7 @@ class Commands(Logger):
         arg:str:pubkey:Public key
         arg:str:message:Clear text message. Use quotes if it contains spaces.
         """
-        if not is_hex_str(pubkey):
-            raise UserFacingException(f"pubkey must be a hex string instead of {repr(pubkey)}")
-        try:
-            message = to_bytes(message)
-        except TypeError:
-            raise UserFacingException(f"message must be a str instead of {repr(message)}")
-        public_key = ecc.ECPubkey(bfh(pubkey))
-        encrypted = crypto.ecies_encrypt_message(public_key, message)
-        return encrypted.decode('utf-8')
+        return Abstract_Wallet.encrypt_message(pubkey=pubkey, message=message)
 
     @command('wp')
     async def decrypt(self, pubkey, encrypted, password=None, wallet: Abstract_Wallet = None) -> str:
diff --git a/electrum/gui/qt/main_window.py b/electrum/gui/qt/main_window.py
index 4811579..de31458 100644
--- a/electrum/gui/qt/main_window.py
+++ b/electrum/gui/qt/main_window.py
@@ -2253,17 +2253,16 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger, QtEventListener):
         pubkey_e: QLineEdit,
         encrypted_e: QTextEdit,
     ) -> None:
-        from electrum import crypto
         message = message_e.toPlainText()
-        message = message.encode('utf-8')
         try:
-            public_key = ecc.ECPubkey(bfh(pubkey_e.text()))
-        except BaseException as e:
-            self.logger.exception('Invalid Public key')
-            self.show_warning(_('Invalid Public key'))
+            encrypted = self.wallet.encrypt_message(
+                pubkey=pubkey_e.text(),
+                message=message,
+            )
+        except UserFacingException as e:
+            self.show_warning(str(e))
             return
-        encrypted = crypto.ecies_encrypt_message(public_key, message)
-        encrypted_e.setText(encrypted.decode('ascii'))
+        encrypted_e.setText(encrypted)
 
     def encrypt_message(self, address: str = "") -> None:
         d = WindowModalDialog(self, _('Encrypt/decrypt Message'))
diff --git a/electrum/wallet.py b/electrum/wallet.py
index e29ccd4..5c02870 100644
--- a/electrum/wallet.py
+++ b/electrum/wallet.py
@@ -48,6 +48,7 @@ from aiorpcx import ignore_after, run_in_thread
 
 from . import util, keystore, transaction, bitcoin, coinchooser, bip32, descriptor
 from . import constants
+from . import crypto
 from .i18n import _
 from .bip32 import BIP32Node, convert_bip32_intpath_to_strpath, convert_bip32_strpath_to_intpath
 from .logging import get_logger, Logger
@@ -56,7 +57,7 @@ from .util import (
     WalletFileException, BitcoinException, InvalidPassword, format_time, timestamp_to_datetime,
     Satoshis, Fiat, TxMinedInfo, quantize_feerate, OrderedDictWithIndex, multisig_type, parse_max_spend,
     OnchainHistoryItem, read_json_file, write_json_file, UserFacingException, FileImportFailed, EventListener,
-    event_listener
+    event_listener, is_hex_str,
 )
 from .bitcoin import COIN, is_address, is_minikey, relayfee, dust_threshold, DummyAddress, DummyAddressUsedInTxException
 from .keystore import (
@@ -3257,6 +3258,22 @@ class Abstract_Wallet(ABC, Logger, EventListener):
         index = self.get_address_index(addr)
         return self.keystore.decrypt_message(index, message, password)
 
+    @classmethod
+    def encrypt_message(cls, *, pubkey: Any | str, message: Any | str) -> str:
+        try:
+            message = util.to_bytes(message)
+        except TypeError:
+            raise UserFacingException(f"message must be a str instead of {type(message)}") from None
+        if not is_hex_str(pubkey):
+            raise UserFacingException(f"pubkey must be a hex string instead of {type(pubkey)}")
+        pubkey_bytes = bytes.fromhex(pubkey)
+        try:
+            eckey = ecc.ECPubkey(pubkey_bytes)
+        except ecc.InvalidECPointException as e:
+            raise UserFacingException(_("Invalid Public key")) from e
+        encrypted = crypto.ecies_encrypt_message(eckey, message)
+        return encrypted.decode("ascii")
+
     @abstractmethod
     def pubkeys_to_address(self, pubkeys: Sequence[str]) -> Optional[str]:
         pass