fix: Frigate face count API structure and Immich 401 error message

Frigate /api/faces response has person names as top-level keys with
lists of filenames — {person: [file, ...], "train": [...]}. The old
code incorrectly looked inside data["train"] as if it were a dict of
persons, causing 'list object has no attribute items' on every run.

Immich get_people() now checks for 401 before raise_for_status() and
logs a clear "API key invalid or expired" message instead of the raw
requests exception string.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

winnow/frigate_api.py

@@ -21,8 +21,13 @@ def get_frigate_face_counts() -> dict[str, int] | None:
         resp = requests.get(f"{frigate_url}/api/faces", timeout=10)
         resp.raise_for_status()
         data = resp.json()
-        train = data.get("train", {})
-        return {name: len(files) for name, files in train.items() if isinstance(files, list)}
+        # Response: {person_name: [file, ...], "train": [...], ...}
+        # "train" is a flat pending list, not a person — skip it.
+        return {
+            name: len(files)
+            for name, files in data.items()
+            if name != "train" and isinstance(files, list)
+        }
     except Exception as e:
         logger.warning(f"Could not query Frigate face counts: {e}")
         return None