fix: Fix hotkey thread-safety issue in Skill Scanner

BUG: TypeError when using F12 hotkey - invokeMethod syntax was wrong
for PyQt6.

FIX:
1. Added hotkey_triggered = pyqtSignal() at class level
2. Connected signal to _scan_page_for_multi in initialize()
3. _hotkey_scan() now just emits the signal (thread-safe)
4. Signal ensures scan runs on main Qt thread

This is the proper Qt way to handle cross-thread communication.
The hotkey callback runs in keyboard library's thread, but the
scan must run in Qt's main thread to update UI safely.

plugins/skill_scanner/plugin.py

@@ -150,6 +150,9 @@ class SkillScannerPlugin(BasePlugin):
     description = "Uses core OCR and Log services"
     hotkey = "ctrl+shift+s"
     
+    # Signal for thread-safe hotkey scanning
+    hotkey_triggered = pyqtSignal()
+    
     def initialize(self):
         """Setup skill scanner."""
         self.data_file = Path("data/skill_tracker.json")
@@ -164,6 +167,9 @@ class SkillScannerPlugin(BasePlugin):
         self.current_scan_session = {}  # Skills collected in current multi-page scan
         self.pages_scanned = 0
         
+        # Connect hotkey signal
+        self.hotkey_triggered.connect(self._scan_page_for_multi)
+        
         # Subscribe to skill gain events from core Log service
         try:
             from core.plugin_api import get_api
@@ -756,12 +762,9 @@ class SkillScannerPlugin(BasePlugin):
             self.auto_scan_active = False
     
     def _hotkey_scan(self):
-        """Scan triggered by F12 hotkey."""
-        from PyQt6.QtCore import QMetaObject, Qt, Q_ARG
-        QMetaObject.invokeMethod(
-            self, "_scan_page_for_multi",
-            Qt.ConnectionType.QueuedConnection
-        )
+        """Scan triggered by F12 hotkey - thread safe via signal."""
+        # Emit signal to safely call from hotkey thread
+        self.hotkey_triggered.emit()
     
     def _check_for_page_change(self):
         """Auto-detect page changes by monitoring page number area."""