fix: round-5 review — constant-time finalized check in missing finalization

The guard-skipped loop tested membership against the finalized list, scanning
up to 200k dicts per missing item — quadratic job finalization that can appear
hung on a large complete import. Test the item's source_key against the
already-built marked_keys set instead.

Author: Coding-Dev-Tools

engraphis/obsidian_import.py

@@ -383,7 +383,7 @@ def import_scan(
                         planned_action="missing", result_state="missing",
                     )
                 for item in missing:
-                    if item in finalized:
+                    if str(item.get("source_key") or "") in marked_keys:
                         continue
                     # The generation guard left this row live: a concurrent import
                     # refreshed it after this run planned it missing. The job history