Rewrite CEF browser as child of Kivy window (v2)

v1 created a separate Win32 window — same problem as external Chrome.
v2 creates CEF as a CHILD WINDOW of Kivy's SDL_app window:
  - No separate taskbar entry
  - No z-order fighting (CEF is INSIDE Kivy)
  - No desktop flash
  - CEF message loop pumped via Kivy Clock (main thread)
  - Resize handler attached so CEF follows Kivy window changes
  - build.spec includes cef_browser in hidden imports

windows/run_win.py

@@ -115,7 +115,12 @@ def _windows_screen_activity(self, dt):
 _CEF_BROWSER = None
 
 def _get_cef_browser():
-    """Return the shared CefBrowser singleton, or None if unavailable."""
+    """Return the shared CefBrowser singleton, or None if unavailable.
+
+    v2 embeds CEF as a CHILD WINDOW inside Kivy's SDL_app window.
+    This means: no separate taskbar entry, no z-order fighting,
+    no desktop flash, no taskkill needed.
+    """
     global _CEF_BROWSER
     if _CEF_BROWSER is None:
         try:
@@ -367,16 +372,37 @@ def _patch_main():
         # ── Strategy 1: CEF embedded browser ────────────────────────
         cef_browser = _get_cef_browser()
         if cef_browser is not None:
-            Logger.info(f"SignagePlayer: Opening weblink via CEF embedded browser: {url}")
+            Logger.info(f"SignagePlayer: Opening weblink via CEF (embedded in Kivy): {url}")
             try:
                 self.ids.content_area.opacity = 0
             except Exception:
                 pass
+            # Attach resize handler so CEF follows Kivy window resizes
+            from kivy.core.window import Window as KivyWindow
+            _orig_on_resize = getattr(KivyWindow, '_on_resize', None)
+            def _cef_resize(*args):
+                try:
+                    w, h = KivyWindow.size
+                    cef_browser.resize(int(w), int(h))
+                except Exception:
+                    pass
+                if _orig_on_resize:
+                    try:
+                        return _orig_on_resize(*args)
+                    except Exception:
+                        pass
+            KivyWindow._on_resize = _cef_resize
+            # Bind to size event as well
+            try:
+                KivyWindow.bind(size=_cef_resize)
+            except Exception:
+                pass
+
             cef_browser.show(url)
             Clock.unschedule(self.next_media)
             self._start_inactivity_watchdog(duration)
             self.preload_next_media()
-            Logger.info("SignagePlayer: CEF browser launched successfully")
+            Logger.info("SignagePlayer: CEF embedded browser visible (inside Kivy window)")
             return True
 
         # ── Strategy 2: Subprocess Chrome/Edge (fallback) ────────────