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/app/db/repositories/syncjob_repository.py

@@ -2,9 +2,16 @@ from sqlalchemy.orm import Session
 from app.db.models import SyncJob
 from sqlalchemy.sql import func
 
+# ---------------------------------------------------------
+# Repositorio de trabajos de sincronización
+# ---------------------------------------------------------
 
 class SyncJobRepository:
 
+    # ---------------------------------------------------------
+    # Función auxiliar: iniciar un nuevo trabajo de sincronización
+    # ---------------------------------------------------------
+
     @staticmethod
     def start_job(db: Session, researcher_id: str):
         job = SyncJob(
@@ -17,6 +24,10 @@ class SyncJobRepository:
         db.refresh(job)
         return job
 
+    # ---------------------------------------------------------
+    # Función auxiliar: finalizar un trabajo de sincronización
+    # ---------------------------------------------------------
+
     @staticmethod
     def finish_job(db: Session, job: SyncJob, new_records: int, updated_records: int):
         job.status = "finished"