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/config.py

@@ -35,11 +35,6 @@ class Settings:
     magpie_host: str
     magpie_user: str
     magpie_container: str
-    whisperx_host: str
-    whisperx_user: str
-    whisperx_container: str
-    whisperx_port: int
-    whisperx_model: str
     ssh_key_path: str
     ssh_known_hosts: str
     models_yaml: str
@@ -54,7 +49,7 @@ class Settings:
     def from_env(cls) -> "Settings":
         spark2_host = _env("SPARK2_HOST")
         spark2_user = _env("SPARK2_USER")
-        # Parakeet, Magpie, and WhisperX all default to Spark 2 unless overridden.
+        # Parakeet and Magpie default to Spark 2 unless explicitly overridden.
         return cls(
             spark1_host=_env("SPARK1_HOST"),
             spark1_user=_env("SPARK1_USER"),
@@ -66,11 +61,6 @@ class Settings:
             magpie_host=_env("MAGPIE_HOST") or spark2_host,
             magpie_user=_env("MAGPIE_USER") or spark2_user,
             magpie_container=_env("MAGPIE_CONTAINER") or "magpie-tts",
-            whisperx_host=_env("WHISPERX_HOST") or spark2_host,
-            whisperx_user=_env("WHISPERX_USER") or spark2_user,
-            whisperx_container=_env("WHISPERX_CONTAINER") or "whisperx-asr",
-            whisperx_port=int(_env("WHISPERX_PORT", "8002")),
-            whisperx_model=_env("WHISPERX_MODEL", "medium"),
             ssh_key_path=_env("SSH_KEY_PATH"),
             ssh_known_hosts=_env("SSH_KNOWN_HOSTS"),
             models_yaml=_resolve_models_yaml(),