refactor: reorganize spec regeneration routes and add unit tests

- Removed the old spec regeneration routes and replaced them with a new structure under the app-spec directory for better modularity.
- Introduced unit tests for common functionalities in app-spec, covering state management and error handling.
- Added documentation on route organization patterns to improve maintainability and clarity for future development.

apps/server/src/routes/spec-regeneration.ts

@@ -1,8 +0,0 @@
-/**
- * Spec Regeneration routes - HTTP API for AI-powered spec generation
- *
- * This file re-exports from the app-spec directory to maintain backward compatibility.
- * The actual implementation has been split into smaller modules in ./app-spec/
- */
-
-export { createSpecRegenerationRoutes } from "./app-spec/index.js";