Add blueprints for authentication, admin, dashboard, gallery, generation, and profile routes

- Created `__init__.py` for blueprint registration.
- Implemented `auth.py` for user authentication (login, register, logout).
- Added `admin.py` for admin functionalities (user management, stats).
- Developed `dashboard.py` for user dashboard displaying user info and generated content.
- Created `gallery.py` for managing and displaying images and videos.
- Implemented `generate.py` for text, image, and video generation functionalities.
- Added `profile.py` for user profile management.
- Updated templates to reflect new route structures and improve navigation.

frontend/app/templates/image_detail.html

@@ -2,7 +2,7 @@
 block content %}
 <div class="container mx-auto px-4 py-8">
   <a
-    href="{{ url_for('gallery') }}"
+    href="{{ url_for('gallery.index') }}"
     class="text-blue-400 hover:underline mb-4 inline-block"
     >&larr; Back to Gallery</a
   >