feat(ui): enhance frontend architecture and improve user experience

Refactor the frontend to use a more consistent design system and improve the overall user interface and experience.

- Implement a consistent use of `Card` components across various pages (Dashboard, Settings, Notes, etc.).
- Improve layout responsiveness and spacing in several modules.
- Enhance the Tasks page with drag-and-drop status updates and a Kanban-style view.
- Update the Calendar view with better color coding for task priorities and types.
- Refactor the Bookmarks page to use a grid layout with improved card previews.
- Update the Nginx configuration to handle SPA routing and health checks more effectively.
- Standardize import paths using `@/` aliases.
- Fix minor bugs in message sending and loading states.
- Update Docker configuration to build from source and use a specific backend port.

frontend/nginx.conf

@@ -39,7 +39,7 @@ http {
         image/svg+xml;
 
     server {
-        listen 80;
+        listen 8080;
         server_name localhost;
         root /usr/share/nginx/html;
         index index.html;
@@ -50,14 +50,39 @@ http {
         add_header X-XSS-Protection "1; mode=block" always;
         add_header Referrer-Policy "strict-origin-when-cross-origin" always;
 
+        # Explicit root files (prevent SPA fallback)
+        location = /manifest.json {
+            try_files $uri =404;
+        }
+        location = /trackeep.svg {
+            try_files $uri =404;
+        }
+        location = /trackeepfavi_bg.png {
+            try_files $uri =404;
+        }
+        location = /trackeepfavi.png {
+            try_files $uri =404;
+        }
+
         # Handle client-side routing
         location / {
             try_files $uri $uri/ /index.html;
         }
 
+        # Health check proxy to backend
+        location /health {
+            proxy_pass http://localhost:8081/health;
+            proxy_http_version 1.1;
+            proxy_set_header Host $host;
+            proxy_set_header X-Real-IP $remote_addr;
+            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+            proxy_set_header X-Forwarded-Proto $scheme;
+            proxy_cache_bypass $http_upgrade;
+        }
+
         # API proxy to backend (internal localhost)
         location /api/ {
-            proxy_pass http://localhost:8080/;
+            proxy_pass http://localhost:8081;
             proxy_http_version 1.1;
             proxy_set_header Upgrade $http_upgrade;
             proxy_set_header Connection 'upgrade';