Drop the unused root hello-world controller, empty CommonModule imports, development seeding code, legacy student report entity, stale DTOs, notification hook, and their placeholder tests.
- Add CommonModule to provide/export CampusScope across business modules
- Replace DepartmentsModule imports with CommonModule in 11 modules
- Add missing Class/Tenant repository imports to StudentsModule and SchedulesModule
- Fix service specs with CampusScope, ClassRepository, StudentRepository mocks
- Move better-sqlite3 to optionalDependencies for production Docker builds
- Rewrite Dockerfiles for monorepo root build context
- Update docker-compose.yml service build contexts
- Move backend/ to apps/server/ via git mv
- Move frontend/ to apps/admin/ via git mv
- Create packages/typescript-config/ with base, nestjs, and react-vite presets
