D2: Widen retry to upload-source jobs

- Remove http-only guard in retry endpoint (src/routes/api/jobs/[id]/retry/+server.ts)
- Extend pipeline.ts retryJob() to handle upload-source jobs:
  read file from persistent storage, pass buffer to runJob
- Change saveUploadedFile() to save to DATA_DIR/uploads/{jobId}/
  (survives cleanupJobTmp, available for retry on failure)
- Add getUploadPath(), cleanupUploadDir() to downloader.ts
- Remove cleanupFiles(rawAudioPath) from catch block in runJob()
  — cleanupJobTmp handles TMP_DIR for YouTube, uploads survive
- Add cleanupUploadDir() on webhook success path
- Add retry-endpoint.test.ts with 9 tests covering:
  - 404 for unknown job
  - 409 for non-retryable status (done, pending)
  - 200 for cancelled (retryable)
  - 200 for failed YouTube job (existing behavior)
  - 200 for failed upload-source job (new behavior, .webm and .mp3)
  - Negative: retryJob not called on 404/409
- Add downloader.test.ts tests for saveUploadedFile persistent path,
  getUploadPath, cleanupUploadDir, isolation, and non-existent cleanup
- Fix webhook.test.ts mock to include cleanupUploadDir

All 189 tests pass across 12 test files.

src/lib/server/pipeline.ts

@@ -1,5 +1,5 @@
 import { createJob, updateJob, setJobStatus, getJob, resetJob } from './db.js';
-import { downloadYouTube, saveUploadedFile, cleanupJobTmp } from './downloader.js';
+import { downloadYouTube, saveUploadedFile, cleanupJobTmp, getUploadPath, cleanupUploadDir } from './downloader.js';
 import { prepareAudio, cleanup as cleanupFiles } from './audio.js';
 import { submitJob, streamJob } from './whisper.js';
 import { ensureWhisperRunning } from './docker.js';
@@ -50,14 +50,25 @@ export async function startUploadJob(
 	return job.id;
 }
 
-/** Retry a failed/cancelled YouTube job by resetting and re-running the pipeline. */
+/** Retry a failed/cancelled job — YouTube or upload-source. */
 export async function retryJob(jobId: string): Promise<void> {
 	const job = getJob(jobId);
 	if (!job) throw new Error('Job not found');
 	resetJob(jobId);
-	runJob(jobId, { type: 'youtube', url: job.source }, job.audioMode as AudioMode).catch((err) => {
-		console.error(`[pipeline] retry job ${jobId} failed:`, err);
-	});
+
+	const isUpload = !job.source.startsWith('http');
+	if (isUpload) {
+		const { readFileSync } = await import('fs');
+		const uploadPath = getUploadPath(jobId, job.source);
+		const buffer = readFileSync(uploadPath);
+		runJob(jobId, { type: 'upload', buffer, filename: job.source }, job.audioMode as AudioMode).catch((err) => {
+			console.error(`[pipeline] retry upload job ${jobId} failed:`, err);
+		});
+	} else {
+		runJob(jobId, { type: 'youtube', url: job.source }, job.audioMode as AudioMode).catch((err) => {
+			console.error(`[pipeline] retry job ${jobId} failed:`, err);
+		});
+	}
 }
 
 async function runJob(
@@ -112,6 +123,7 @@ async function runJob(
 			const { sendNotification } = await import('./push.js');
 			await sendNotification(jobId, '✅ Transcript ready', title);
 			await cleanupJobTmp(jobId);
+		await cleanupUploadDir(jobId).catch(() => {});
 			return;
 		}
 
@@ -162,7 +174,9 @@ async function runJob(
 		const message = err instanceof Error ? err.message : String(err);
 		updateJob({ id: jobId, status: 'failed', error: message });
 		emitProgress(jobId, { type: 'error', message });
-		if (rawAudioPath) await cleanupFiles(rawAudioPath).catch(() => {});
+		// rawAudioPath NOT cleaned here — for upload jobs the file lives in
+		// DATA_DIR/uploads/{jobId}/ so it survives for retry. For YouTube jobs,
+		// cleanupJobTmp below handles TMP_DIR/{jobId} which contains the audio.
 		if (wavPath) await cleanupFiles(wavPath).catch(() => {});
 		await cleanupJobTmp(jobId);
 	}