fix: refuse unavailable gallery and pin head trainer

recognization/code/app.py

@@ -293,8 +293,11 @@ def create_app(
 
     scans = scans if scans is not None else build_legacy_scans(engine)
     # A live session can be recorded so a real scan becomes data to label later.
-    recorder = FrameRecorder(settings.record_frames, every=settings.record_every) \
-        if settings.record_frames else None
+    recorder = FrameRecorder(
+        settings.record_frames,
+        every=settings.record_every,
+        identity_backend=engine.settings.identity_backend,
+    ) if settings.record_frames else None
     samples = {item["id"]: item for item in get_available_shelf_images("add")}
     # path -> (mtime_ns, size, width, height). Dropped when the file changes.
     sample_dimensions: Dict[str, Tuple[int, int, int, int]] = {}
@@ -1138,7 +1141,8 @@ def main() -> None:
     engine = build_default_engine(engine_settings)
     if (engine_settings.identity_backend or "").lower() == "gallery":
         if engine.identity_gallery() is None:
-            raise RuntimeError(
+            engine.shutdown()
+            raise SystemExit(
                 "gallery identity backend requires local DINOv2 weights; refusing to start"
             )
     warm_ms = engine.warm_up()