v0.13.0:0 - revert WhisperX migration; back to Parakeet + Sortformer

After five hotfix iterations on the WhisperX install (v0.12.0:0–:4) we
never got a working docker build. The fundamental constraint isn't
patchable from outside NVIDIA: NGC PyTorch on ARM64 (the only base that
runs on Spark 2's GB10 Blackwell) ships a custom-versioned torch
2.10.0a0+b558c98 that has no pre-built torchaudio match anywhere.
WhisperX → pyannote → torchaudio is a hard dependency chain we couldn't
satisfy without rebuilding torchaudio against torch 2.10's alpha API.
Walking away cleanly is better than another night of chasing.

Removed from the codebase:
  - image/whisperx_container/* (Dockerfile + requirements + app/main.py)
  - image/app/whisperx_install.py (install manager + SSH ship-context logic)
  - image/Dockerfile COPY whisperx_container
  - WHISPERX_* config keys in config.py
  - whisperx service entry in services.py
  - WhisperX-preferred branch in audio_proxy.py
  - /api/whisperx/* endpoints in server.py
  - install banner + progress dialog in index.html
  - render + handlers in app.js
  - .whisperx-install styles in style.css

Spark 2 cleaned in tandem (user-authorized): container removed,
~/whisperx-build/ removed, 5.4 GB of dangling image layers + 1.3 GB of
builder cache reclaimed. parakeet-asr and magpie-tts unaffected and
healthy throughout.

The audio path is back to exactly what shipped in v0.11.0:3:
  POST /api/audio/transcribe-with-speakers
    → Parakeet (transcription) + Sortformer (diarization) in parallel
    → merged by timestamp into speaker-labeled blocks

v0.13.0:1+ will add the actually-needed fixes that the WhisperX detour
was meant to address:
  1. memory cap on the parakeet-asr container so a long-audio crash
     can't swap-thrash Spark 2 again
  2. a chunking proxy in /api/audio/transcribe-with-speakers that
     splits inputs >10 min before Sortformer

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

image/app/services.py

@@ -65,14 +65,6 @@ def services_from_settings(s: Settings) -> dict[str, ServiceDef]:
             container=s.magpie_container,
             port=s.magpie_port,
         ),
-        "whisperx": ServiceDef(
-            name="whisperx",
-            kind="stt+diarize",
-            host=s.whisperx_host,
-            user=s.whisperx_user,
-            container=s.whisperx_container,
-            port=s.whisperx_port,
-        ),
     }
     for entry in load_custom_services():
         key = entry.get("key")