feat: complete PRD verification fixes and deployment readiness

- 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

apps/server/src/app.module.ts

@@ -54,7 +54,7 @@ import { ClassroomRentalsModule } from './classroom-rentals/classroom-rentals.mo
 import { SyncModule } from './sync/sync.module';
 import { NotificationsModule } from './notifications/notifications.module';
 import { DepartmentsModule } from './departments/departments.module';
-import { CampusScope } from './common/campus-scope';
+import { CommonModule } from './common/common.module';
 import { CampusScopeMiddleware } from './common/campus-scope.middleware';
 
 @Module({
@@ -139,9 +139,9 @@ import { CampusScopeMiddleware } from './common/campus-scope.middleware';
     SyncModule,
     NotificationsModule,
     DepartmentsModule,
+    CommonModule,
   ],
   providers: [
-    CampusScope,
     { provide: APP_GUARD, useClass: ThrottlerGuard },
     { provide: APP_GUARD, useClass: JwtAuthGuard },
     { provide: APP_GUARD, useClass: PermissionGuard },