perf: skip ffmpeg transcode for PocketTTS streaming — use WAV directly

PocketTTS emits 16-bit PCM WAV (16 kHz mono). WAV is natively supported
on all browsers including iOS/macOS Safari, so the ffmpeg MP3 transcode
is unnecessary for the streaming path.

Using format=wav for PocketTTS voices eliminates the ffmpeg subprocess
startup delay (~200–400 ms) and a pipeline stage, giving lower latency
to first audio frame. Kokoro and CF AI continue using MP3 (they output
MP3 natively or via the OpenAI-compatible endpoint).

The runner (MinIO storage) is unaffected — it still stores MP3 for
space efficiency.

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

ui/messages/id.json

@@ -302,6 +302,24 @@
   "book_detail_range_queuing": "Mengantri…",
   "book_detail_scrape_range": "Rentang scrape",
   "book_detail_admin": "Admin",
+  "book_detail_admin_book_cover": "Sampul Buku",
+  "book_detail_admin_chapter_cover": "Sampul Bab",
+  "book_detail_admin_chapter_n": "Bab #",
+  "book_detail_admin_description": "Deskripsi",
+  "book_detail_admin_chapter_names": "Nama Bab",
+  "book_detail_admin_audio_tts": "Audio TTS",
+  "book_detail_admin_voice": "Suara",
+  "book_detail_admin_generate": "Buat",
+  "book_detail_admin_save_cover": "Simpan Sampul",
+  "book_detail_admin_saving": "Menyimpan…",
+  "book_detail_admin_saved": "Tersimpan",
+  "book_detail_admin_apply": "Terapkan",
+  "book_detail_admin_applying": "Menerapkan…",
+  "book_detail_admin_applied": "Diterapkan",
+  "book_detail_admin_discard": "Buang",
+  "book_detail_admin_enqueue_audio": "Antre Audio",
+  "book_detail_admin_cancel_audio": "Batal",
+  "book_detail_admin_enqueued": "Diantre {enqueued}, dilewati {skipped}",
   "book_detail_scraping_progress": "Mengambil 20 bab pertama. Halaman ini akan dimuat ulang otomatis.",
   "book_detail_scraping_home": "← Beranda",
   "book_detail_rescrape_book": "Scrape ulang buku",