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/mcp/messageTrackingTransport.ts

@@ -1,6 +1,17 @@
-import type { Transport, TransportSendOptions } from "@modelcontextprotocol/client";
-import type { JSONRPCMessage, MessageExtraInfo } from "@modelcontextprotocol/client";
-import type { JSONRPCRequest, JSONRPCNotification, JSONRPCResultResponse, JSONRPCErrorResponse } from "@modelcontextprotocol/client";
+import type {
+  Transport,
+  TransportSendOptions,
+} from "@modelcontextprotocol/client";
+import type {
+  JSONRPCMessage,
+  MessageExtraInfo,
+} from "@modelcontextprotocol/client";
+import type {
+  JSONRPCRequest,
+  JSONRPCNotification,
+  JSONRPCResultResponse,
+  JSONRPCErrorResponse,
+} from "@modelcontextprotocol/client";
 import type { MessageOrigin } from "./types.js";
 
 export interface MessageTrackingCallbacks {
@@ -21,10 +32,7 @@ export class MessageTrackingTransport implements Transport {
   private callbacks: MessageTrackingCallbacks;
   private negotiatedProtocolVersion?: string;
 
-  constructor(
-    baseTransport: Transport,
-    callbacks: MessageTrackingCallbacks,
-  ) {
+  constructor(baseTransport: Transport, callbacks: MessageTrackingCallbacks) {
     this.baseTransport = baseTransport;
     this.callbacks = callbacks;
   }