fix(captures): Play As autoplay + default voice + orphan recovery

- Hand /generate ids to the global SSE watcher so playback fires on completion. The mutation onSuccess was checking audio_path on a queued row, which is always empty — autoplay never ran.
- Bind the Play As voice selection to capture_settings.default_playback_voice_id, kept in sync with the Settings → Captures and Settings → MCP pickers. Picking from the split-button dropdown writes back to settings.
- Extract AudioBars from HistoryTable into a shared component; use it for the Play As generating state in place of Loader2.
- Stop the active-state hover from flashing white text when the button is in its lighter accent/10 fill.
- Drop the gradient avatar swatches from the Settings → Captures voice dropdown.
- Backend: when the gen worker exits without writing a terminal status (e.g. SQLite lock racing the failed-status write inside its own exception handler), the cancel endpoint now flips the row to failed instead of 409-ing. Worker also force-fails on its way out as a belt-and-suspenders.

backend/services/task_queue.py

@@ -56,12 +56,43 @@ async def _generation_worker():
                     raise
         except Exception:
             traceback.print_exc()
+            await _force_fail_if_active(
+                job.generation_id,
+                "Worker exited without writing terminal status",
+            )
         finally:
             _running_generation_tasks.pop(job.generation_id, None)
             _queued_generation_ids.discard(job.generation_id)
             _generation_queue.task_done()
 
 
+async def _force_fail_if_active(generation_id: str, error: str) -> None:
+    """Best-effort recovery — flip an active row to failed if the worker
+    bailed before writing a terminal status. Catches the case where the gen
+    coroutine's own status-write raised (e.g. SQLite lock contention)."""
+    try:
+        from ..database import Generation as DBGeneration, get_db
+        from . import history
+
+        db = next(get_db())
+        try:
+            gen = db.query(DBGeneration).filter_by(id=generation_id).first()
+            if gen is None:
+                return
+            if (gen.status or "completed") not in ("loading_model", "generating"):
+                return
+            await history.update_generation_status(
+                generation_id=generation_id,
+                status="failed",
+                db=db,
+                error=error,
+            )
+        finally:
+            db.close()
+    except Exception:
+        traceback.print_exc()
+
+
 def enqueue_generation(generation_id: str, coro):
     """Add a generation coroutine to the serial queue."""
     if _generation_queue is None: