fix: address 5 code review findings (round 5)

- embeddings: move os.close into try/finally so saved_out/saved_err are
  always closed even when os.dup2 restore raises, preventing fd leak
- cache: replace narrow except tuple with except MemoryError: raise /
  except Exception: return None so struct.error and other np.load failures
  return None without masking OOM
- executor: fix first-run advisory message to check effective_count == 0
  (post-stale-cleanup) instead of pre_run_count; remove now-unused
  pre_run_count variable entirely
- jobs: remove dead "skip" entry from strategy_map (unreachable since the
  early-return at the top of _resolve_strategy fires first)
- upload_tracker: log a warning when reset_person encounters a non-list
  flat_key value instead of silently skipping the cleanup

winnow/executor.py

@@ -327,7 +327,6 @@ def upload_to_frigate(jobs: list[dict]) -> None:
             # TODO(frigate-api): if Frigate exposes per-file embeddings, compute
             # diversity against the full training set (tracked + manual) rather than
             # relying solely on the Frigate score as a proxy signal.
-            pre_run_count = get_tracked_frigate_file_count(name)
             _snapshot = (
                 all_frigate_files.get(name, []) if all_frigate_files is not None
                 else get_frigate_person_files(name)
@@ -360,7 +359,7 @@ def upload_to_frigate(jobs: list[dict]) -> None:
                     )
             effective_count = get_tracked_frigate_file_count(name)
             quality_replacement = job.get("config", {}).get("quality_replacement", False)
-            if Config.ENABLE_FRIGATE_SCORES and pre_run_count == 0:
+            if Config.ENABLE_FRIGATE_SCORES and effective_count == 0:
                 progress.console.print(
                     f"  [dim]{name}: first run — Frigate diversity scoring will apply from the next run[/dim]"
                 )