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>

specification/v2_ux_interfaces.md

@@ -356,7 +356,7 @@ will close out as part of that work.
 - **Purpose**: Search + method filter sidebar for the history screen.
 - **Current props**: `searchText`, `methodFilter`, `onSearchChange`, `onMethodFilterChange`.
 - **MCP schema touch points**: Method filter values are MCP `Request.method` literals.
-- **Target props**: `searchText`, `methodFilter?: RequestMethod`, `availableMethods: RequestMethod[]`, `onSearchChange`, `onMethodFilterChange`.
+- **Target props**: `searchText`, `methodFilter?: MessageMethod`, `availableMethods: MessageMethod[]`, `onSearchChange`, `onMethodFilterChange`.
 - **Callbacks → core hook**: `useMessageLog`.
 - **Internal refactors**: Type the method filter as a union of MCP method strings.