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/auth/oauth-storage.ts

@@ -1,5 +1,12 @@
-import type { OAuthClientInformation, OAuthTokens, OAuthMetadata } from "@modelcontextprotocol/client";
-import { OAuthClientInformationSchema, OAuthTokensSchema } from "@modelcontextprotocol/core";
+import type {
+  OAuthClientInformation,
+  OAuthTokens,
+  OAuthMetadata,
+} from "@modelcontextprotocol/client";
+import {
+  OAuthClientInformationSchema,
+  OAuthTokensSchema,
+} from "@modelcontextprotocol/core";
 import type { OAuthStorage } from "./storage.js";
 import { type OAuthMemoryStore, type ServerOAuthState } from "./store.js";
 import type { OAuthPersistBackend } from "./oauth-persist.js";
@@ -173,7 +180,9 @@ export class OAuthStorageBase implements OAuthStorage {
 
   async clearCodeVerifier(serverUrl: string): Promise<void> {
     await this.ensureLoaded();
-    this.memory.getState().setServerState(serverUrl, { codeVerifier: undefined });
+    this.memory
+      .getState()
+      .setServerState(serverUrl, { codeVerifier: undefined });
     await this.persist();
   }
 
@@ -206,7 +215,9 @@ export class OAuthStorageBase implements OAuthStorage {
     metadata: OAuthMetadata,
   ): Promise<void> {
     await this.ensureLoaded();
-    this.memory.getState().setServerState(serverUrl, { serverMetadata: metadata });
+    this.memory
+      .getState()
+      .setServerState(serverUrl, { serverMetadata: metadata });
     await this.persist();
   }