feat: enhance backend security and configuration

- Updated Dockerfile to improve security with a non-root user and added health checks.
- Modified docker-compose.yml to set containers as read-only, restrict ports to localhost, and implement health checks.
- Enhanced .env.example with additional environment variables for security and configuration.
- Improved FastAPI application with middleware for security headers, CORS, and body size limits.
- Refactored authentication flow in auth.py to include state validation and improved error handling.
- Added rate limiting to various endpoints to prevent abuse.
- Updated researcher and publication handling to ensure better validation and error management.

backend/requirements.txt

@@ -1,14 +1,16 @@
 fastapi
-uvicorn
+uvicorn[standard]
 sqlalchemy
 psycopg2-binary
 httpx
 pydantic
+pydantic-settings
 python-dotenv
 lxml
-apscheduler
+defusedxml
+APScheduler==3.10.4
 authlib
 redis
-APScheduler==3.10.4
 requests
 python-jose[cryptography]
+slowapi