fix(tts): fix pocket-tts voices missing in UI and 500 on first TTS enqueue

- Add POCKET_TTS_URL env to backend service in docker-compose.yml so
  pocket-tts voices appear in the voice selector (Doppler secret existed
  but the env var was never passed to the container)
- Fix GetAudioTask PocketBase filter using %q (double-quotes) instead of
  single-quoted string, causing the duplicate-task guard to always miss
- Fix AudioPlayer double-POST: GET /api/presign/audio already enqueues
  TTS internally on 404; AudioPlayer now skips the redundant POST and
  polls directly, eliminating the 500 from the PB unique-key conflict

ui/src/lib/components/AudioPlayer.svelte

@@ -343,23 +343,28 @@
 
 	// ── API helpers ────────────────────────────────────────────────────────────
 
+	type PresignResult =
+		| { ready: true; url: string }
+		| { ready: false; enqueued: boolean }; // enqueued=true → presign already POSTed
+
 	async function tryPresign(
 		targetSlug: string,
 		targetChapter: number,
 		targetVoice: string
-	): Promise<string | null> {
+	): Promise<PresignResult> {
 		const params = new URLSearchParams({
 			slug: targetSlug,
 			n: String(targetChapter),
 			voice: targetVoice
 		});
 		const res = await fetch(`/api/presign/audio?${params}`);
-		// 202: TTS was just enqueued by the presign endpoint — audio not ready yet.
+		// 202: presign endpoint already triggered TTS — skip the POST, go straight to polling.
 		// 404: legacy fallback (should no longer occur after endpoint change).
-		if (res.status === 202 || res.status === 404) return null;
+		if (res.status === 202) return { ready: false, enqueued: true };
+		if (res.status === 404) return { ready: false, enqueued: false };
 		if (!res.ok) throw new Error(`presign HTTP ${res.status}`);
 		const data = (await res.json()) as { url: string };
-		return data.url;
+		return { ready: true, url: data.url };
 	}
 
 	type AudioStatusResponse =
@@ -421,50 +426,52 @@
 
 		try {
 			// Fast path: already generated
-			const url = await tryPresign(slug, nextChapter, voice);
-			if (url) {
+			const presignResult = await tryPresign(slug, nextChapter, voice);
+			if (presignResult.ready) {
 				stopNextProgress();
 				audioStore.nextProgress = 100;
-				audioStore.nextAudioUrl = url;
+				audioStore.nextAudioUrl = presignResult.url;
 				audioStore.nextStatus = 'prefetched';
 				return;
 			}
 
-			// Slow path: trigger Kokoro generation (non-blocking POST), then poll.
-			const res = await fetch(`/api/audio/${slug}/${nextChapter}`, {
-				method: 'POST',
-				headers: { 'Content-Type': 'application/json' },
-				body: JSON.stringify({ voice })
-			});
-			if (!res.ok) throw new Error(`Prefetch generation failed: HTTP ${res.status}`);
+			// Slow path: trigger generation (or skip POST if presign already enqueued).
+			if (!presignResult.enqueued) {
+				const res = await fetch(`/api/audio/${slug}/${nextChapter}`, {
+					method: 'POST',
+					headers: { 'Content-Type': 'application/json' },
+					body: JSON.stringify({ voice })
+				});
+				if (!res.ok) throw new Error(`Prefetch generation failed: HTTP ${res.status}`);
 
-			// Whether the server returned 200 (already cached) or 202 (enqueued),
-			// always presign — the status endpoint no longer returns a proxy URL.
-			if (res.status === 200) {
-				// Body is { status: 'done' } — audio confirmed in MinIO. Presign it.
-				await res.body?.cancel();
-			}
-			// else 202: generation enqueued — fall through to poll.
-
-			if (res.status !== 200) {
-				// 202: poll until done.
-				const final = await pollAudioStatus(slug, nextChapter, voice);
-				stopNextProgress();
-				audioStore.nextProgress = 100;
-
-				if (final.status === 'failed') {
-					throw new Error(`Prefetch failed: ${(final as { error?: string }).error ?? 'unknown'}`);
+				if (res.status === 200) {
+					// Body is { status: 'done' } — audio confirmed in MinIO. Presign it.
+					await res.body?.cancel();
+					stopNextProgress();
+					audioStore.nextProgress = 100;
+					const doneUrl = await tryPresign(slug, nextChapter, voice);
+					if (!doneUrl.ready) throw new Error('Prefetch: audio done but presign returned 404');
+					audioStore.nextAudioUrl = doneUrl.url;
+					audioStore.nextStatus = 'prefetched';
+					return;
 				}
-			} else {
-				stopNextProgress();
-				audioStore.nextProgress = 100;
+				// 202: generation enqueued — fall through to poll.
+			}
+
+			// Poll until done (covers both: presign-enqueued and POST-enqueued paths).
+			const final = await pollAudioStatus(slug, nextChapter, voice);
+			stopNextProgress();
+			audioStore.nextProgress = 100;
+
+			if (final.status === 'failed') {
+				throw new Error(`Prefetch failed: ${(final as { error?: string }).error ?? 'unknown'}`);
 			}
 
 			// Audio is ready in MinIO — get a direct presigned URL.
 			const doneUrl = await tryPresign(slug, nextChapter, voice);
-			if (!doneUrl) throw new Error('Prefetch: audio done but presign returned 404');
+			if (!doneUrl.ready) throw new Error('Prefetch: audio done but presign returned 404');
 
-			audioStore.nextAudioUrl = doneUrl;
+			audioStore.nextAudioUrl = doneUrl.url;
 			audioStore.nextStatus = 'prefetched';
 		} catch {
 			stopNextProgress();
@@ -532,9 +539,9 @@
 			}
 
 			// Fast path B: audio already in MinIO (presign check).
-			const url = await tryPresign(slug, chapter, voice);
-			if (url) {
-				audioStore.audioUrl = url;
+			const presignResult = await tryPresign(slug, chapter, voice);
+			if (presignResult.ready) {
+				audioStore.audioUrl = presignResult.url;
 				audioStore.status = 'ready';
 				// Restore last saved position after the audio element loads
 				restoreSavedAudioTime();
@@ -547,33 +554,44 @@
 			audioStore.status = 'generating';
 			startProgress();
 
-			const res = await fetch(`/api/audio/${slug}/${chapter}`, {
-				method: 'POST',
-				headers: { 'Content-Type': 'application/json' },
-				body: JSON.stringify({ voice })
-			});
-			if (!res.ok) throw new Error(`Generation failed: HTTP ${res.status}`);
+			// presignResult.enqueued=true means /api/presign/audio already POSTed on our
+			// behalf — skip the duplicate POST and go straight to polling.
+			if (!presignResult.enqueued) {
+				const res = await fetch(`/api/audio/${slug}/${chapter}`, {
+					method: 'POST',
+					headers: { 'Content-Type': 'application/json' },
+					body: JSON.stringify({ voice })
+				});
+				if (!res.ok) throw new Error(`Generation failed: HTTP ${res.status}`);
 
-			if (res.status !== 200) {
-				// 202: generation enqueued — poll until done.
-				const final = await pollAudioStatus(slug, chapter, voice);
-
-				if (final.status === 'failed') {
-					throw new Error(
-						`Generation failed: ${(final as { error?: string }).error ?? 'unknown error'}`
-					);
+				if (res.status === 200) {
+					// Already cached — body is { status: 'done' }, no url needed.
+					await res.body?.cancel();
+					await finishProgress();
+					const doneUrl = await tryPresign(slug, chapter, voice);
+					if (!doneUrl.ready) throw new Error('Audio generated but presign returned 404');
+					audioStore.audioUrl = doneUrl.url;
+					audioStore.status = 'ready';
+					maybeStartPrefetch();
+					return;
 				}
-			} else {
-				// 200: already cached — body is { status: 'done' }, no url needed.
-				await res.body?.cancel();
+				// 202: fall through to polling below.
+			}
+
+			// Poll until the runner finishes generating.
+			const final = await pollAudioStatus(slug, chapter, voice);
+			if (final.status === 'failed') {
+				throw new Error(
+					`Generation failed: ${(final as { error?: string }).error ?? 'unknown error'}`
+				);
 			}
 
 			await finishProgress();
 
 			// Audio is ready in MinIO — always use a presigned URL for direct playback.
 			const doneUrl = await tryPresign(slug, chapter, voice);
-			if (!doneUrl) throw new Error('Audio generated but presign returned 404');
-			audioStore.audioUrl = doneUrl;
+			if (!doneUrl.ready) throw new Error('Audio generated but presign returned 404');
+			audioStore.audioUrl = doneUrl.url;
 			audioStore.status = 'ready';
 			// Don't restore time for freshly generated audio — position is 0
 			// Immediately start pre-generating the next chapter in background.