chore(deployment): add docker-compose and nginx setup for production

- Added Dockerfile and nginx.conf for frontend production build.
- Added docker-compose.yml to orchestrate backend and frontend.
- Updated geminiService.ts to support relative API paths via Nginx proxy.
- Updated documentation with deployment instructions for Synology/Docker.

general-market-intelligence/Dockerfile

@@ -0,0 +1,27 @@
+# Stage 1: Build the React App
+FROM node:18-alpine as build
+
+WORKDIR /app
+
+# Copy package files first for better caching
+COPY package.json package-lock.json ./
+RUN npm install
+
+# Copy source code
+COPY . .
+
+# Build for production
+RUN npm run build
+
+# Stage 2: Serve with Nginx
+FROM nginx:alpine
+
+# Copy built assets from Stage 1
+COPY --from=build /app/dist /usr/share/nginx/html
+
+# Copy custom Nginx config
+COPY nginx.conf /etc/nginx/conf.d/default.conf
+
+EXPOSE 80
+
+CMD ["nginx", "-g", "daemon off;"]