feat: deploy through shared Caddy ingress

docker/frontend.Dockerfile

@@ -0,0 +1,41 @@
+FROM node:24-alpine AS builder
+
+WORKDIR /app
+COPY package.json package-lock.json ./
+RUN npm ci
+COPY . .
+RUN npm run build
+
+FROM nginxinc/nginx-unprivileged:1.29-alpine
+
+COPY --from=builder /app/build /usr/share/nginx/html
+RUN <<'EOF' cat > /etc/nginx/conf.d/default.conf
+server {
+    listen 8080;
+    server_name _;
+    root /usr/share/nginx/html;
+    index index.html;
+    server_tokens off;
+
+    location = /healthz {
+        access_log off;
+        default_type text/plain;
+        return 200 "ok\n";
+    }
+
+    location ~* \.(?:css|js|woff2|png|jpg|jpeg|gif|svg|webp|ico)$ {
+        try_files $uri =404;
+        expires 1y;
+        add_header Cache-Control "public, max-age=31536000, immutable";
+    }
+
+    location / {
+        try_files $uri $uri/ /index.html;
+        add_header Cache-Control "no-cache";
+    }
+}
+EOF
+
+EXPOSE 8080
+HEALTHCHECK --interval=10s --timeout=3s --start-period=15s --retries=5 \
+  CMD wget -qO- http://127.0.0.1:8080/healthz || exit 1