feat: migrate to DragonflyDB and clean up environment configuration

- Replace Redis with DragonflyDB for better performance and memory efficiency
- Remove redundant environment variables (POSTGRES_*, ENCRYPTION_KEY, OAUTH_SERVICE_URL)
- Consolidate database configuration to use single DB_* variables
- Use JWT_SECRET for both JWT tokens and encryption
- Remove PORT variable redundancy, use BACKEND_PORT consistently
- Clean up docker-compose configurations for dev/prod consistency
- Add DragonflyDB configuration with optimized memory usage
- Remove redis.conf as it's no longer needed
- Update health checks to use Redis-compatible CLI for DragonflyDB

frontend/Dockerfile

@@ -11,15 +11,14 @@ ARG VITE_API_URL=http://localhost:8080
 COPY frontend/package*.json ./frontend/
 RUN cd frontend && npm install --include=dev
 
-# Copy environment variables and source code
-COPY ../.env ./frontend/.env
-COPY . ./frontend/
+# Copy frontend source code only
+COPY frontend/ ./frontend/
 
 # Create a .env.production file with build arguments
 RUN cd frontend && echo "VITE_DEMO_MODE=${VITE_DEMO_MODE}" >> .env.production && \
     echo "VITE_API_URL=${VITE_API_URL}" >> .env.production
 
-# Build the application
+# Build the application (frontend only)
 RUN cd frontend && npm run build
 
 # Production stage
@@ -38,7 +37,7 @@ COPY frontend/nginx.conf /etc/nginx/nginx.conf
 # Make a backup of the original index.html for runtime substitution
 RUN cp /usr/share/nginx/html/index.html /usr/share/nginx/html/index.html.orig
 
-# Expose port 80
+# Expose port (will be dynamically set by entrypoint)
 EXPOSE 80
 
 # Start the entrypoint script