feat(profile): implement user-initiated GDPR-compliant profile deletion

- Add DELETE /users/me endpoint with cascading data removal
- Implement frontend confirmation dialog and deletion flow
- Add audit logging for deletion requests
- Update localization files for new UI strings
- Add scheduled cleanup service for AI traces
- Document GDPR compliance in technical specification

BREAKING CHANGE: Users can now permanently delete their profiles and associated data

backend/package.json

@@ -24,6 +24,7 @@
     "@nestjs/jwt": "^11.0.2",
     "@nestjs/passport": "^11.0.5",
     "@nestjs/platform-express": "^11.1.19",
+    "@nestjs/schedule": "^6.1.3",
     "@nestjs/throttler": "^6.4.0",
     "@prisma/client": "6.12.0",
     "bcryptjs": "^2.4.3",