fix(validator): preserve handler name for telemetry and logs

[sjorobekov]

Summary

Fixes an issue where withContract swallowed the wrapped handler's .name, causing all contracted routes to be logged and reported in telemetry as "finalHandler".

• Adds operationId?: string to RouteContract (OpenAPI-canonical).
• withContract now sets the wrapper's name to config.operationId || handler.name || ''.
• Anonymous handlers without an operationId now correctly fall through to the router's UNNAMED_CONTROLLER fallback instead of leaking the internal "finalHandler" name.
• Updated documentation and added tests.