Phase 5 audit: annotate spec, close HistoryControls partial

Audited every component under clients/web/src/components/ against its
v2_ux_interfaces.md entry. Added an "Audit results" section near the top
of the spec with the verified count (57/62 satisfied, 5 partial) and the
specific gaps still open.

While auditing, closed the HistoryControls gap directly:

- Added RequestMethod union type to core/mcp/types.ts, derived from the
  SDK's Client/Server Request and Notification schemas plus a synthetic
  "response" entry for result/error MessageEntries.
- Typed methodFilter and onMethodFilterChange in HistoryControls,
  HistoryListPanel, historyUtils.extractMethod with RequestMethod.
- Lifted the hardcoded METHOD_OPTIONS list out of HistoryControls into
  a required availableMethods prop. HistoryScreen now derives it from
  the live entries via useMemo + extractMethod.
- Updated HistoryControls.stories.tsx to pass availableMethods.

The remaining 5 partials (ElicitationUrlPanel, InlineElicitationRequest,
InlineSamplingRequest, ExperimentalFeaturesPanel, ResourceListItem) are
either blocked on the v2 core hook layer effort or call out follow-up
work that has its own design questions.

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

clients/web/src/components/groups/historyUtils.ts

@@ -1,8 +1,11 @@
-import type { MessageEntry } from "../../../../../core/mcp/types.js";
+import type {
+  MessageEntry,
+  RequestMethod,
+} from "../../../../../core/mcp/types.js";
 
-export function extractMethod(entry: MessageEntry): string {
+export function extractMethod(entry: MessageEntry): RequestMethod {
   if ("method" in entry.message) {
-    return entry.message.method;
+    return entry.message.method as RequestMethod;
   }
   return "response";
 }