fix: resolve wifi crashes, shell injections, race conditions, and add debug mode

- Remove transient NEED_AUTH/DISCONNECTED error paths from wifi connect
- Guard double-callback in connect_wifi_bssid/connect_wifi_with_password
- Shell-quote user paths in wallpaper, screenshot, screenrecorder services
- Fix OSD hide-timer use-after-free and applet_window stale source ID
- Fix brightness poll timer leak on read failure
- Fix spotlight search stale idle source removal
- Lock dbusmenu _cache mutation under _registry_lock
- Fix entry.revision written outside _registry_lock scope
- Add fabric-cli exec wrapper for lock screen (lock_screen.lock())
- Replace hyprlock with lock screen in power menu and dropdown
- Add debug mode toggle in settings (controls log verbosity)
- Add diagnostic logging to globalmenu click chain

src/services/brightness.py

@@ -93,7 +93,8 @@ class Brightness(Service):
             return True
         except Exception as e:
             logger.error(f"Error checking brightness file: {e}")
-            return True
+            self._poll_timer_id = None
+            return False
 
     def _detect_backend(self, backend):
         """Detect appropriate backend for brightness control."""