feat: add frontend nginx image and update build workflow for both images

nginx.conf

@@ -0,0 +1,29 @@
+server {
+    listen 80;
+    root /usr/share/nginx/html;
+    index index.html;
+
+    # Proxy API and WebDAV to backend
+    location /v1/ {
+        proxy_pass http://localhost:8000;
+        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;
+    }
+
+    location /webdav/ {
+        proxy_pass http://localhost:8000;
+        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;
+    }
+
+    # SPA fallback — all other routes serve index.html
+    location / {
+        try_files $uri $uri/ /index.html;
+    }
+}