feat(TRUEREF-0022): complete iteration 0 — worker-thread indexing, parallel jobs, SSE progress

- Move IndexingPipeline.run() into Worker Threads via WorkerPool
- Add dedicated embedding worker thread with single model instance
- Add stage/stageDetail columns to indexing_jobs schema
- Create ProgressBroadcaster for SSE channel management
- Add SSE endpoints: GET /api/v1/jobs/:id/stream, GET /api/v1/jobs/stream
- Replace UI polling with EventSource on repo detail and admin pages
- Add concurrency settings UI and API endpoint
- Build worker entries separately via esbuild

src/lib/server/pipeline/indexing.pipeline.test.ts

@@ -28,7 +28,8 @@ function createTestDb(): Database.Database {
 		'0000_large_master_chief.sql',
 		'0001_quick_nighthawk.sql',
 		'0002_silky_stellaris.sql',
-		'0003_multiversion_config.sql'
+		'0003_multiversion_config.sql',
+		'0004_complete_sentry.sql'
 	]) {
 		const migrationSql = readFileSync(join(migrationsFolder, migrationFile), 'utf-8');