chore(db): re-export playgroundPresets from localDb

Adds one re-export block at the end of localDb.ts per Hard Rule #2
(re-export only, zero logic, zero function/const/class additions).

src/lib/localDb.ts

@@ -508,3 +508,13 @@ export {
 } from "./db/freeProxies";
 
 export type { FreeProxyRecord, FreeProxyStats } from "./db/freeProxies";
+
+export {
+  listPlaygroundPresets,
+  getPlaygroundPreset,
+  createPlaygroundPreset,
+  updatePlaygroundPreset,
+  deletePlaygroundPreset,
+} from "./db/playgroundPresets";
+
+export type { PlaygroundPresetListItem } from "./db/playgroundPresets";