Address @claude review: format core/, typed output-validation error, document progress heuristic

- Run Prettier on the 60 core/ files this PR touched — the deterministic
  import rewrite had collapsed multi-line imports and left throws unwrapped;
  core/ is in no format gate so it slipped past CI. Now Prettier-clean.
- Default-path output-schema violation now throws
  ProtocolError(ProtocolErrorCode.InvalidParams, …) instead of a bare Error,
  matching the prior v1 contract (SDK threw a typed McpError with a code) so
  downstream `instanceof`/`.code` branching keeps working.
- Document the "assumes serial construction" invariant on pollTaskToolCall's
  progress-subscription revival (the `_progressHandlers` new-key heuristic).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

core/react/usePagedRequestorTasks.ts

@@ -39,10 +39,7 @@ export function usePagedRequestorTasks(
     setTasks(pagedRequestorTasksState.getTasks());
     setNextCursor(pagedRequestorTasksState.getNextCursor() ?? undefined);
     const onTasksChange = (
-      event: TypedEventGeneric<
-        PagedRequestorTasksStateEventMap,
-        "tasksChange"
-      >,
+      event: TypedEventGeneric<PagedRequestorTasksStateEventMap, "tasksChange">,
     ) => {
       setTasks(event.detail);
       setNextCursor(pagedRequestorTasksState.getNextCursor() ?? undefined);