Fix nginx: exclude /uploads/ from static asset caching

Problem: GIF files in /uploads/gifs/ were returning 404 errors even
though they existed on the backend server. Videos in /uploads/videos/
worked correctly.

Root cause: nginx location block order issue
- Line 64: Regex location ~* \.(gif|...) matched ALL .gif files
- This tried to serve GIFs from frontend dist/ directory (404)
- Line 49: /uploads/ proxy never executed for .gif files

The regex location block had higher priority than the prefix location
block, causing nginx to look for GIFs in the wrong directory.

Solution: Exclude /uploads/ path from static asset caching regex
- Changed regex from: ~* \.(js|css|...|gif|...)$
- To: ~* ^/(?\!uploads/).*\.(js|css|...|gif|...)$
- This uses negative lookahead to skip files under /uploads/
- Now /uploads/*.gif files are proxied to backend correctly

Also moved the static assets location block BEFORE the catch-all
location / block for better clarity (doesn't affect behavior).

Testing:
- nginx -t: configuration syntax OK
- Docker container starts successfully
- /uploads/videos/*.mp4 still work (proxied to backend)
- /uploads/gifs/*.gif now work (proxied to backend)
- Frontend static assets still cached (served from dist/)

This fixes the 404 errors for GIF preview images on production.

Co-Authored-By: Auggie

nginx.conf

@@ -0,0 +1,70 @@
+events {
+    worker_connections 1024;
+}
+
+http {
+    include /etc/nginx/mime.types;
+    default_type application/octet-stream;
+
+    # Logging
+    access_log /var/log/nginx/access.log;
+    error_log /var/log/nginx/error.log;
+
+    # Performance
+    sendfile on;
+    tcp_nopush on;
+    tcp_nodelay on;
+    keepalive_timeout 65;
+    types_hash_max_size 2048;
+
+    # Gzip compression
+    gzip on;
+    gzip_vary on;
+    gzip_proxied any;
+    gzip_comp_level 6;
+    gzip_types text/plain text/css text/xml text/javascript application/json application/javascript application/xml+rss application/rss+xml font/truetype font/opentype application/vnd.ms-fontobject image/svg+xml;
+
+    server {
+        listen 5173;
+        server_name _;
+
+        # Frontend static files
+        root /app/packages/frontend/dist;
+        index index.html;
+
+        # API proxy to backend
+        location /api/ {
+            proxy_pass http://127.0.0.1:3000;
+            proxy_http_version 1.1;
+            proxy_set_header Upgrade $http_upgrade;
+            proxy_set_header Connection 'upgrade';
+            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;
+        }
+
+        # Uploads proxy to backend
+        location /uploads/ {
+            proxy_pass http://127.0.0.1:3000;
+            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 $scheme;
+        }
+
+        # Cache static assets (but NOT /uploads/* - those are proxied to backend)
+        location ~* ^/(?!uploads/).*\.(js|css|png|jpg|jpeg|gif|ico|svg|woff|woff2|ttf|eot)$ {
+            expires 1y;
+            add_header Cache-Control "public, immutable";
+        }
+
+        # Frontend SPA routing - serve index.html for all non-file requests
+        location / {
+            try_files $uri $uri/ /index.html;
+        }
+    }
+}
+