feat: add gallery page with image and video details, including upload and generation status

Co-authored-by: Copilot <copilot@github.com>

frontend/app/templates/base.html

@@ -21,6 +21,7 @@
         <div class="nav-links">
           {% if session.get('access_token') %}
           <a href="{{ url_for('dashboard') }}">Dashboard</a>
+          <a href="{{ url_for('gallery') }}">Gallery</a>
 
           <a href="{{ url_for('generate_text') }}">Generate Text</a>
           <a href="{{ url_for('generate_image') }}">Generate Image</a>