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/services/sword_generator.py

@@ -6,6 +6,9 @@ ATOM_NS = "http://www.w3.org/2005/Atom"
 DC_NS = "http://purl.org/dc/elements/1.1/"
 EXTRA_NS = "http://example.org/orcid-extra"   # namespace para campos extendidos
 
+# ---------------------------------------------------------
+# Clase de generador de feed SWORD
+# ---------------------------------------------------------
 
 class SWORDGenerator: