fix: audit remediation — SSE user scoping, FK transactional safety, UI error handling

- H4: scoped SSE import progress to exact userId match; non-HTTP events excluded from all subscribers
- H2: moved PRAGMA foreign_key_check inside SQLite transaction before COMMIT; violations rollback preserving old tables
- M1: removed dead axios-style error branch from extractErrorMessage (interceptor already unwraps)
- M2: split handleSave try/catch — save errors vs reload errors shown distinctly
- M3: added provider field validation before AI config test request
- Added SSE scoping regression tests (import service + controller)
- Added FK check failure rollback test (database-migrations.spec)
- Updated controller spec expectations for userId parameter

Co-authored-by: Code Review <branch-review>

apps/server/src/app.module.ts

@@ -28,6 +28,7 @@ import {
   ClassTeacher,
   ClassSchedule,
   AttendanceRecord,
+  AttendanceSession,
   DingAttendanceRaw,
   SyncLog,
   SyncState,
@@ -116,6 +117,7 @@ import { IntegrationConfigModule } from './integration/config/config.module';
           Role,
           ClassSchedule,
           AttendanceRecord,
+          AttendanceSession,
           DingAttendanceRaw,
           Notification,
           StudentProfile,