Implement security headers middleware with HSTS and permissions policy

[Smartdevs17]

Context

Implement security measures for implement security headers middleware with hsts and permissions policy.

Current Limitation

This functionality is currently missing or needs improvement.

Expected Outcome

• Production-ready implementation
• Comprehensive test coverage
• Documentation and examples
• Performance benchmarks where applicable

Acceptance Criteria

• Feature implemented with full functionality
• Unit tests added with >80% coverage
• Integration tests for critical paths
• No regression introduced
• Documentation updated
• Code review approved
• Performance benchmarks met

Technical Scope

backend/src/middleware/security.ts, backend/src/config.ts

Labels

• drips-wave
• high
• 200-points