Refactor static serving: use Blueprint static_folder, inline header

- Disable Flask default /static/ folder (static_folder=None in app.py)
- Add headerRoute blueprint to serve views/header/ at /assets/header/
- Configure transcription and scraper blueprints with static_folder
  pointing to their respective views/ subfolders
- Inline header HTML directly in headerLoader.js (remove fetch call)
- Update all HTML templates to use new /assets/... URLs

routes/headerRoute.py

@@ -0,0 +1,11 @@
+# routes/headerRoute.py
+from flask import Blueprint
+
+# Blueprint để serve headerLoader.js từ views/header/
+# → URL: /assets/header/headerLoader.js
+header_bp = Blueprint(
+    'header',
+    __name__,
+    static_folder='../views/header',
+    static_url_path='/assets/header',
+)