fix(recipes): eliminate O(n) fuzzy search fallback over 42k+ recipes

Drop the SequenceMatcher-based fuzzy_match fallback that froze the server
when FTS returned empty results. FTS now returns empty set for zero results
(no fallback), and when the index is not yet ready, search returns empty
rather than scanning all items in Python.

tests/services/test_recipe_scanner.py

@@ -77,7 +77,15 @@ def recipe_scanner(tmp_path: Path, monkeypatch):
     monkeypatch.setattr(config, "loras_roots", [str(tmp_path)])
     stub = StubLoraScanner()
     scanner = RecipeScanner(lora_scanner=stub)
-    asyncio.run(scanner.refresh_cache(force=True))
+
+    async def _init():
+        await scanner.refresh_cache(force=True)
+        # Wait for FTS index build to finish — asyncio.run()
+        # cancels background tasks on return, so we must await it here.
+        if scanner._fts_index_task:
+            await scanner._fts_index_task
+
+    asyncio.run(_init())
     yield scanner, stub
     RecipeScanner._instance = None
     settings_manager_module.reset_settings_manager()