fix: Add missing register_window_service to PluginAPI

BUG: App crashed on startup with AttributeError:
'PluginAPI' object has no attribute 'register_window_service'

FIX:
- Added register_window_service() method to PluginAPI
- Added get_eu_window() convenience method
- Added is_eu_focused() convenience method
- Added is_eu_visible() convenience method
- Added bring_eu_to_front() convenience method

All window manager methods accessible via PluginAPI:
- api.get_eu_window()
- api.is_eu_focused()
- api.is_eu_visible()
- api.bring_eu_to_front()

App now starts correctly on Windows.

core/plugin_api.py

@@ -1142,6 +1142,65 @@ class PluginAPI:
         
         return clipboard.paste()
 
+    # ========== Window Manager Service ==========
+
+    def register_window_service(self, window_manager) -> None:
+        """Register the Window Manager service.
+        
+        Args:
+            window_manager: WindowManager instance from core.window_manager
+        """
+        self.services['window'] = window_manager
+        print("[API] Window Manager service registered")
+
+    def get_eu_window(self) -> Optional[Dict[str, Any]]:
+        """Get information about the Entropia Universe game window.
+        
+        Returns:
+            Dict with window info or None if not found
+        """
+        window_manager = self.services.get('window')
+        if not window_manager:
+            return None
+        
+        return window_manager.find_eu_window()
+
+    def is_eu_focused(self) -> bool:
+        """Check if Entropia Universe window is currently focused.
+        
+        Returns:
+            True if EU is the active window
+        """
+        window_manager = self.services.get('window')
+        if not window_manager:
+            return False
+        
+        return window_manager.is_eu_focused()
+
+    def is_eu_visible(self) -> bool:
+        """Check if Entropia Universe window is visible.
+        
+        Returns:
+            True if EU window is visible (not minimized)
+        """
+        window_manager = self.services.get('window')
+        if not window_manager:
+            return False
+        
+        return window_manager.is_eu_visible()
+
+    def bring_eu_to_front(self) -> bool:
+        """Bring Entropia Universe window to front and focus it.
+        
+        Returns:
+            True if successful
+        """
+        window_manager = self.services.get('window')
+        if not window_manager:
+            return False
+        
+        return window_manager.bring_eu_to_front()
+
     # ========== Data Store Service ==========
 
     def register_data_service(self, data_store) -> None: