v0.12.0:0 - WhisperX as a one-click dashboard install + managed service

Replaces the manual rsync+build+run with a proper spark-control feature.
First in the audio path that doesn't require shell access on Spark 2.

What's in the box
─────────────────
* image/whisperx_container/   - the build context (Dockerfile, requirements,
  app/main.py FastAPI wrapper). Mainline pipeline: faster-whisper for STT +
  pyannote 3.1 for diarization + wav2vec2 forced alignment. Single endpoint
  /v1/audio/transcribe-with-speakers returns the exact same shape spark-
  control's existing endpoint does, so the recap-relay PR spec needs no
  changes when we cut over.

* image/app/whisperx_install.py - install manager. ships build context to
  Spark 2 over SSH, runs `docker build`, runs `docker run` with 40 GB
  memory cap (vs Sortformer's unbounded which thrashed Spark 2 on a 90-min
  file), polls /health until both Whisper + pyannote report loaded.

* Audio proxy: /api/audio/transcribe-with-speakers now prefers WhisperX
  when its /health reports diarizer_loaded=true, falls back to the legacy
  Parakeet + Sortformer path otherwise. Same response shape either way.
  Clean cutover, easy rollback (`docker rm whisperx-asr`).

* Dashboard (Audio / Speech tab):
  - "Add WhisperX" banner appears when not installed, with a primary
    "Install WhisperX" button. One click triggers the install.
  - Build progress dialog with phase + elapsed timer + live build log via
    SSE (`/api/whisperx/install/{job_id}/stream`).
  - After install, WhisperX auto-registers as a managed service alongside
    Parakeet and Magpie (Start/Restart/Stop, deep-check, auto-restart).
  - Banner self-hides once /api/whisperx/status reports healthy.

New endpoints
─────────────
  GET  /api/whisperx/status
  POST /api/whisperx/install
  GET  /api/whisperx/install/{job_id}
  GET  /api/whisperx/install/{job_id}/stream  (SSE phase + log)

Config additions (env)
──────────────────────
  WHISPERX_HOST       (defaults to spark2_host)
  WHISPERX_USER       (defaults to spark2_user)
  WHISPERX_CONTAINER  (default: whisperx-asr)
  WHISPERX_PORT       (default: 8002)
  WHISPERX_MODEL      (default: medium; tiny/base/small/medium/large-v3)

Dockerfile
──────────
Added COPY whisperx_container /app/whisperx_container so the runtime
install manager can read the build context from inside the spark-control
image and ship it over SSH.

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

image/app/static/index.html

@@ -103,6 +103,46 @@
 
     <div class="tab-content" id="tab-audio" role="tabpanel" aria-labelledby="tab-audio-trigger">
 
+    <section id="whisperx-install-card" class="whisperx-install hidden">
+      <div class="wx-install-body">
+        <div class="wx-install-title">
+          <strong>Add WhisperX</strong>
+          <span class="tag ok">recommended</span>
+        </div>
+        <p class="muted small">
+          WhisperX is a single-container speech pipeline (faster-whisper for transcription + pyannote 3.1 for diarization)
+          designed to handle long audio cleanly. Replaces the Parakeet + Sortformer combo we patched together,
+          which crashed on a 90-min meeting. Pulled and built directly on Spark 2 (~10–15 min first time;
+          you only do this once).
+        </p>
+        <p class="muted small">
+          Requires a Hugging Face token at <code>~/.cache/huggingface/token</code> on Spark 2 (already set up).
+        </p>
+        <div class="wx-install-actions">
+          <button id="wx-install" class="btn primary">Install WhisperX</button>
+        </div>
+      </div>
+    </section>
+
+    <dialog id="whisperx-progress-dialog" class="modal">
+      <form method="dialog" class="modal-form">
+        <h3 id="wx-prog-title">Installing WhisperX…</h3>
+        <div class="phase-row">
+          <span class="spinner"></span>
+          <div class="phase" id="wx-prog-phase">Starting…</div>
+          <span class="spacer"></span>
+          <span class="timer" id="wx-prog-elapsed">0:00</span>
+        </div>
+        <details open>
+          <summary class="muted small">Build log</summary>
+          <pre id="wx-prog-log" class="log"></pre>
+        </details>
+        <div class="modal-actions">
+          <button type="button" id="wx-prog-close" class="btn">Close</button>
+        </div>
+      </form>
+    </dialog>
+
     <section id="services-panel" class="services hidden">
       <div class="section-header">
         <h2 class="section-title">Always-on services</h2>