Fix: Invisible overlay blocking mouse clicks

Problem:
The overlay window, even when fully transparent or visually hidden (opacity 0), was still intercepting mouse events. This created a 'dead zone' on the screen where users could not click through to applications behind the overlay. This occurred because the low-level window hook was answering 'HTCAPTION' to hit tests regardless of the UI state.

Solution:
1. Modified 'WindowHook' to accept an 'enabled' state.
2. When disabled, 'WM_NCHITTEST' now returns 'HTTRANSPARENT', allowing the OS to pass the click to the window underneath.
3. Updated 'main.py' to toggle this hook state dynamically:
   - ENABLED when Recording or Processing (UI is visible/active).
   - DISABLED when Idling (UI is hidden/transparent).

Result:
The overlay is now completely non-intrusive when not in use.

src/utils/window_hook.py

@@ -65,6 +65,10 @@ class WindowHook:
         # (Window 420x140, Pill 380x100)
         self.logical_rect = [20, 20, 20+380, 20+100]
         self.current_scale = initial_scale
+        self.enabled = True # New flag
+
+    def set_enabled(self, enabled):
+        self.enabled = enabled
 
     def install(self):
         proc_address = ctypes.cast(self.new_wnd_proc, ctypes.c_void_p)
@@ -73,6 +77,10 @@ class WindowHook:
     def wnd_proc_callback(self, hwnd, msg, wParam, lParam):
         try:
             if msg == WM_NCHITTEST:
+                # If disabled (invisible/inactive), let clicks pass through (HTTRANSPARENT)
+                if not self.enabled:
+                    return HTTRANSPARENT
+                    
                 res = self.on_nchittest(lParam)
                 if res != 0: 
                     return res