fix(lit-query): merge @template JSDoc into main doc block for useMutationState

Two adjacent JSDoc blocks caused TypeScript's language service to shadow
the @param/@returns/@example docs with the @template block. Merge them
into a single block so IntelliSense shows the full documentation on hover.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: junjuny0227

packages/lit-query/src/useMutationState.ts

@@ -206,8 +206,7 @@ class MutationStateController<
  *   }
  * }
  * ```
- */
-/**
+ *
  * @template TResult - The type of values returned by the `select` callback.
  * @template TMutation - Narrows the type of the `mutation` argument passed to
  * `select`. This is a caller-side assertion — the mutation cache stores