chore(docker): optimize Dockerfiles and add healthchecks for Coolify deployment

- Add build arguments and environment variables for OAuth client IDs in frontend Dockerfile
- Install wget and add HEALTHCHECK commands to frontend and backend Dockerfiles
- Create non-root user in backend Dockerfile for improved security
- Update docker-compose.yml with healthcheck configurations and dynamic port/environment variable support
- Add network configuration and restart policies to docker-compose services
- Expand .env.example with additional OAuth secrets, ports, and environment variables for Coolify
- Enhance README.md with detailed Coolify deployment instructions and required environment variables table

server/Dockerfile

@@ -1,4 +1,4 @@
-# Backend Dockerfile
+# Backend Dockerfile (Coolify Optimized)
 FROM node:20-alpine AS builder
 
 WORKDIR /app
@@ -20,6 +20,9 @@ FROM node:20-alpine
 
 WORKDIR /app
 
+# Install wget for healthcheck
+RUN apk add --no-cache wget
+
 # Copy package files and install production deps only
 COPY package*.json ./
 RUN npm ci --only=production
@@ -27,6 +30,14 @@ RUN npm ci --only=production
 # Copy built code
 COPY --from=builder /app/dist ./dist
 
+# Create non-root user for security
+RUN addgroup -g 1001 -S nodejs && \
+    adduser -S nodejs -u 1001
+USER nodejs
+
 EXPOSE 3001
 
+HEALTHCHECK --interval=30s --timeout=10s --start-period=10s --retries=3 \
+    CMD wget -q --spider http://localhost:3001/health || exit 1
+
 CMD ["node", "dist/index.js"]