ci: add Drone pipeline, production Docker setup, frontend Dockerfile

frontend/Dockerfile

@@ -0,0 +1,24 @@
+# ── Stage 1: Build ────────────────────────────────────────────────────────────
+FROM node:20-alpine AS build
+
+ARG VITE_API_URL=http://localhost:4000/api
+ENV VITE_API_URL=$VITE_API_URL
+
+WORKDIR /app
+
+COPY package*.json ./
+RUN npm ci --ignore-scripts
+
+COPY . .
+RUN npm run build
+
+# ── Stage 2: Serve ────────────────────────────────────────────────────────────
+FROM nginx:1.27-alpine
+
+COPY --from=build /app/dist /usr/share/nginx/html
+COPY nginx.conf /etc/nginx/conf.d/default.conf
+
+EXPOSE 80
+
+HEALTHCHECK --interval=30s --timeout=5s --start-period=5s --retries=3 \
+  CMD wget -qO- http://localhost/health || exit 1