Rebuild .exe with CEF + win32gui fixes

- Updated build.spec with win32gui/win32con hidden imports
- Updated requirements_win.txt with cefpython3 docs
- Rebuilt .exe at 2026-07-24 14:41 (143 MB with CEF)
- All 12 resources bundled (icons, intro1.mp4)
- development-track.md updated with BUG-007, BUG-008

windows/_check_syntax.py

@@ -0,0 +1,18 @@
+"""Quick syntax check for build files."""
+import ast, sys
+
+files = [
+    r'c:\Users\Dell-PC\Desktop\Kiwy-Signage\windows\run_win.py',
+    r'c:\Users\Dell-PC\Desktop\Kiwy-Signage\windows\pyi_runtime_hook.py',
+]
+
+for f in files:
+    try:
+        with open(f, encoding='utf-8') as fh:
+            ast.parse(fh.read())
+        print(f"OK: {f}")
+    except SyntaxError as e:
+        print(f"SYNTAX ERROR in {f}: {e}")
+        sys.exit(1)
+
+print("All files OK")