fix(MULTIVERSION-0001): fix multi-version indexing — jobs never created or triggered for secondary versions

Two bugs prevented secondary versions from ever being indexed:

1. JobQueue.enqueue() and RepositoryService.createIndexingJob() deduplication
   only checked repository_id, so a queued default-branch job blocked all
   version-specific jobs for the same repo. Fix: include version_id in the
   WHERE clause so only exact (repository_id, version_id) pairs are deduped.

2. POST /api/v1/libs/:id/versions used repoService.createIndexingJob() which
   inserts a job record but never triggers queue processing. Fix: use
   queue.enqueue() (same fallback pattern as the libs endpoint) so setImmediate
   fires processNext() after the job is inserted.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/lib/server/services/repository.service.test.ts

@@ -529,4 +529,24 @@ describe('RepositoryService.createIndexingJob()', () => {
 		const job = service.createIndexingJob('/facebook/react', '/facebook/react/v18.3.0');
 		expect(job.versionId).toBe('/facebook/react/v18.3.0');
 	});
+
+	it('allows separate jobs for the same repo but different versions', () => {
+		const defaultJob = service.createIndexingJob('/facebook/react');
+		const versionJob = service.createIndexingJob('/facebook/react', '/facebook/react/v18.3.0');
+		expect(versionJob.id).not.toBe(defaultJob.id);
+		expect(defaultJob.versionId).toBeNull();
+		expect(versionJob.versionId).toBe('/facebook/react/v18.3.0');
+	});
+
+	it('returns the existing job when the same (repo, version) pair is already queued', () => {
+		const job1 = service.createIndexingJob('/facebook/react', '/facebook/react/v18.3.0');
+		const job2 = service.createIndexingJob('/facebook/react', '/facebook/react/v18.3.0');
+		expect(job2.id).toBe(job1.id);
+	});
+
+	it('returns the existing default-branch job when called again without a versionId', () => {
+		const job1 = service.createIndexingJob('/facebook/react');
+		const job2 = service.createIndexingJob('/facebook/react');
+		expect(job2.id).toBe(job1.id);
+	});
 });