feat: add retry/delete for jobs

- db.ts: add resetJob() and deleteJob() statements + exports
- pipeline.ts: export retryJob() — resets job state and re-runs pipeline
- DELETE /api/jobs/[id]: hard-delete terminal jobs (done/failed/cancelled);
  keep cancel-only behavior for active jobs
- POST /api/jobs/[id]/retry: new endpoint; validates failed/cancelled URL job,
  resets and re-runs via retryJob()
- jobs/[id]/+page.svelte: wire Cancel/Retry/Delete buttons with fetch calls;
  fix hardcoded ACCENT → accent store
- jobs/+page.svelte: per-row Retry+Delete icon buttons (visible on hover);
  fix hardcoded ACCENT → accent store

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

src/routes/api/jobs/[id]/+server.ts

@@ -1,5 +1,6 @@
 import { json, error } from '@sveltejs/kit';
-import { getJob, setJobStatus } from '$lib/server/db.js';
+import { getJob, setJobStatus, deleteJob } from '$lib/server/db.js';
+import { rm } from 'fs/promises';
 
 export async function GET({ params }) {
 	const job = getJob(params.id);
@@ -7,12 +8,19 @@ export async function GET({ params }) {
 	return json(job);
 }
 
+const ACTIVE = new Set(['pending', 'downloading', 'preparing', 'transcribing', 'processing']);
+
 export async function DELETE({ params }) {
 	const job = getJob(params.id);
 	if (!job) throw error(404, 'Job not found');
-	if (job.status === 'done' || job.status === 'failed') {
-		throw error(409, 'Job already completed');
+
+	if (ACTIVE.has(job.status)) {
+		// Cancel active job (keeps DB record)
+		setJobStatus(params.id, 'cancelled', 0);
+	} else {
+		// Hard-delete terminal job + clean up output files
+		deleteJob(params.id);
+		if (job.outputDir) rm(job.outputDir, { recursive: true, force: true }).catch(() => {});
 	}
-	setJobStatus(params.id, 'cancelled', 0);
 	return new Response(null, { status: 204 });
 }