fix(notion-search): warn on --filter without --databases + DRY cache_kwargs

Inline code review polish:
- --filter is only meaningful in per-database mode (workspace search
  doesn't accept Notion filter objects). Previously a user passing
  --filter without --databases would have it silently parsed and
  ignored. Now emit a stderr warning and clear the filter.
- cache_kwargs dict was built twice in run_search (once for cache_get,
  once for cache_put). Build once before the rerank call.

30/30 tests still pass.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

custom-skills/31-notion-organizer/code/scripts/notion_search.py

@@ -380,8 +380,10 @@ def run_search(
         ]
 
     candidate_ids = [c["id"] for c in enriched]
+    # Pass cache_dir only if explicitly set; otherwise let _search_cache use its default.
+    cache_kwargs = {"cache_dir": cache_dir} if cache_dir else {}
+
     if use_cache:
-        cache_kwargs = {"cache_dir": cache_dir} if cache_dir else {}
         cached = _search_cache.cache_get(query, candidate_ids, **cache_kwargs)
         if cached is not None:
             return cached
@@ -389,7 +391,6 @@ def run_search(
     ranked = rerank(query, enriched, llm_caller=rerank_llm, limit=limit)
 
     if use_cache:
-        cache_kwargs = {"cache_dir": cache_dir} if cache_dir else {}
         _search_cache.cache_put(query, candidate_ids, ranked, **cache_kwargs)
 
     return ranked
@@ -444,6 +445,10 @@ def main():
     # Parse databases and filter
     databases = args.databases.split(",") if args.databases else None
     prop_filter = json.loads(args.filter) if args.filter else None
+    if prop_filter and not databases:
+        print("Warning: --filter is only applied in per-database mode; ignored without --databases",
+              file=sys.stderr)
+        prop_filter = None
 
     # Build notion client
     api_key = os.getenv("NOTION_API_KEY") or os.getenv("NOTION_TOKEN")