feat: add weblink playlists, SSH player deployment, Caddy HTTPS, build player page

- Content model: add url column + is_weblink() for web page content items
- Player model: add deployment tracking fields (status, timestamps, message)
- Content blueprint: add add_weblink and add_weblink_to_playlist routes;
  weblinks auto-deleted when removed from playlist
- Players blueprint: add SSH deploy mode in add_player; weblink-aware playlist
- API blueprint: weblink URL served directly in playlist response;
  add /api/deploy/test-ssh and /api/deploy/player endpoints
- Admin blueprint: add build-player page (clone from Gitea, write base config);
  replace nginx status card with Caddy status on HTTPS config page
- caddy_manager: rewritten to generate proper HTTPS/internal-CA Caddyfiles
  and reload Caddy via admin API (/load) for live config updates
- ssh_deploy, background_tasks, player_build: new utils for SSH deployment
- background_tasks: push Flask app context into background thread so DB
  updates after deployment complete correctly
- ssh_deploy: robust install script detection with passwordless sudo injection
  (uses SSH credentials, cleaned up after install)
- Dockerfile: add git, sshpass, openssh-client, rsync
- docker-compose: switch nginx to Caddy on ports 80/443; add port 5000 for dev
- Templates: add_player deploy mode UI, weblink form in playlist/upload pages,
  build_player admin page, Caddy status on HTTPS config page
- Migrations: add_url_to_content, add_deployment_fields_to_player
- app.py: call db.create_all() on startup for schema bootstrap
- config.py: add PLAYER_CODE_DIR and PLAYER_REPO_URL settings

app/templates/admin/admin.html

@@ -95,6 +95,17 @@
         </div>
     </div>
 
+    <!-- Build Player Files Card (Admin Only) -->
+    <div class="card management-card" style="background: linear-gradient(135deg, #11998e 0%, #38ef7d 100%);">
+        <h2>🚀 Build Player Files</h2>
+        <p>Clone/refresh the player code from Gitea and configure the server address for deployment</p>
+        <div class="card-actions">
+            <a href="{{ url_for('admin.build_player') }}" class="btn btn-primary">
+                Build Player Files
+            </a>
+        </div>
+    </div>
+
     <!-- Logo Customization Card (Admin Only) -->
     <div class="card management-card" style="background: linear-gradient(135deg, #fa709a 0%, #fee140 100%);">
         <h2>🎨 Logo Customization</h2>