Address PR #1236 review feedback

- Rename RequestMethod → MessageMethod. The type covers notifications and
  results, not just requests; the new name matches the JSDoc.
- Normalize imports to the @inspector/core/mcp/types.js path alias in
  HistoryListPanel, historyUtils, and HistoryScreen (HistoryControls was
  already using the alias).
- Document the cast invariant in extractMethod: SDK types message.method
  as string, but every MessageEntry in this app originates from SDK
  schemas, so the narrowing is safe.
- Type SAMPLE_METHODS as MessageMethod[] in HistoryControls stories so
  the literal-type narrowing isn't lost across the spread.

Skipped two reviewer suggestions: the Mantine Select inline cast (reviewer
self-resolved) and the stale-methodFilter-on-clear UX edge case (deferred
as a separate follow-up — not a Phase 5 audit gap).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

core/mcp/types.ts

@@ -103,7 +103,7 @@ export interface MessageEntry {
 }
 
 /** Method name for any MessageEntry traffic, plus synthetic "response" for result/error entries. */
-export type RequestMethod =
+export type MessageMethod =
   | ClientRequest["method"]
   | ClientNotification["method"]
   | ServerRequest["method"]