Add request ID middleware to trace requests through the system. The middleware checks for existing X-Request-ID headers, generates a new UUID if not present, and sets the ID in both request/response headers and Gin context.
Add admin and master authentication layers with JWT support. Replace direct
key creation with hierarchical master/child key system. Update database
schema to support master accounts with configurable limits and epoch-based
key revocation. Add health check endpoint with system status monitoring.
BREAKING CHANGE: Removed direct POST /keys endpoint in favor of master-based
key issuance through /v1/tokens. Database migration requires dropping old User
table and creating Master table with new relationships.