feat: per-window detection — only flash windows needing attention

Detector now walks each AXWindow subtree independently and returns
both aggregate signals (for state machine) and a list of AXWindow
element refs for windows with active approval signals.

Overlay reads position/size directly from AXWindow elements via
AXValueGetValue, eliminating the CGWindowList dependency (which
returned empty names for Electron windows anyway).

Daemon passes only the active AXWindow refs to the overlay, so
only the specific window(s) waiting for user input get flashed.

Made-with: Cursor

src/cursor_flasher/daemon.py

@@ -46,9 +46,9 @@ class FlasherDaemon:
         self._running = False
 
     def _tick(self) -> None:
-        signals = self.detector.poll()
+        result = self.detector.poll()
 
-        if signals is None:
+        if result is None:
             if self.state_machine.state == FlasherState.WAITING_FOR_USER:
                 self.state_machine.dismiss()
                 self.overlay.hide()
@@ -56,8 +56,8 @@ class FlasherDaemon:
             return
 
         changed = self.state_machine.update(
-            agent_working=signals.agent_working,
-            approval_needed=signals.approval_needed,
+            agent_working=result.signals.agent_working,
+            approval_needed=result.signals.approval_needed,
         )
 
         if not changed:
@@ -74,9 +74,8 @@ class FlasherDaemon:
 
         match self.state_machine.state:
             case FlasherState.WAITING_FOR_USER:
-                pid = self.detector._pid
-                if pid is not None:
-                    self.overlay.show(pid)
+                if result.active_windows:
+                    self.overlay.show(result.active_windows)
                     play_alert(self.config)
                     self._waiting_since = time.monotonic()
             case FlasherState.AGENT_WORKING | FlasherState.IDLE: