feat: add reset synced data button to settings

mobile/db/queries.ts

@@ -103,6 +103,13 @@ export async function upsertRemoteActivity(
   return result.changes > 0;
 }
 
+export async function deleteRemoteActivities(
+  db: ReturnType<typeof useSQLiteContext>,
+): Promise<number> {
+  const result = await db.runAsync(`DELETE FROM activities WHERE origin = 'remote'`);
+  return result.changes;
+}
+
 // ── Settings ───────────────────────────────────────────────────────────────
 
 export async function getSetting(