feat(frontend): add Dockerfile and nginx.conf for ConfigMap

frontend/Dockerfile

@@ -0,0 +1,14 @@
+FROM nginx:alpine
+
+# Static assets
+COPY index.html /usr/share/nginx/html/
+COPY style.css /usr/share/nginx/html/
+COPY app.js /usr/share/nginx/html/
+
+# nginx.conf is provided at runtime via ConfigMap mount.
+# We do NOT copy it into the image; the default nginx.conf in the image
+# would be used if the ConfigMap mount is missing.
+
+EXPOSE 80
+
+CMD ["nginx", "-g", "daemon off;"]

nginx.conf

@@ -0,0 +1,38 @@
+worker_processes  1;
+
+events {
+    worker_connections  1024;
+}
+
+http {
+    include       mime.types;
+    default_type  application/octet-stream;
+    sendfile      on;
+    keepalive_timeout 65;
+
+    large_client_header_buffers 4 32k;
+
+    upstream api_backend {
+        server api:5000;
+    }
+
+    server {
+        listen       80;
+        server_name  localhost;
+
+        root /usr/share/nginx/html;
+        index index.html;
+
+        location / {
+            try_files $uri $uri/ /index.html;
+        }
+
+        location /api/ {
+            proxy_pass http://api_backend;
+            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;
+        }
+    }
+}