fix: surface list-fetch failures instead of swallowing them

A list load that failed — a transport error, or a result the SDK's era
codec rejects as invalid — reported nothing. The connect-time refresh is
fired with no caller to await it (`void this.refresh()`), so its rejection
became an unhandled rejection: the header said "Connected", the panel
rendered an empty list indistinguishable from a server that has none, and
the failed exchange showed in the Protocol panel as a clean success.

Two surfaces now tell the truth:

- ManagedListState records the failure as observable state (`getError` +
  an `errorChange` event) and still re-throws, so App's auth-recovery
  wrapper keeps working. The four `useManaged*` hooks expose it via a
  shared `useManagedListError`, and the Tools/Prompts/Resources sidebars
  render a `ListLoadError` alert with the reason and a Retry.
- A response the client refused is attributed back to its Protocol entry
  (`markResponseRejected` → `responseRejected` → `MessageEntry.clientError`),
  which now renders an Error status and a "Rejected by the Inspector"
  alert rather than the green resultType badge alone. The SDK gives no
  request id with a decode failure, so the id is recovered by correlation;
  see the comment on `markResponseRejected` for why that is exact.

Also stops `listAllTools` from dropping a failing excluded-tools walk on
the floor — it stays non-fatal but is logged.

Closes #1953

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SW1p8E2uiyyLx4RKwrwSrt

clients/web/src/App.tsx

@@ -994,24 +994,33 @@ function App() {
   } = useInspectorClient(inspectorClient);
   const {
     tools: managedTools,
+    error: toolsLoadError,
     listChanged: toolsListChanged,
     refresh: refreshTools,
     clearListChanged: clearToolsListChanged,
   } = useManagedTools(inspectorClient, managedToolsState);
   const {
     prompts: managedPrompts,
+    error: promptsLoadError,
     listChanged: promptsListChanged,
     refresh: refreshPrompts,
     clearListChanged: clearPromptsListChanged,
   } = useManagedPrompts(inspectorClient, managedPromptsState);
   const {
     resources: managedResources,
+    error: resourcesLoadError,
     listChanged: resourcesListChanged,
     refresh: refreshResources,
     clearListChanged: clearResourcesListChanged,
   } = useManagedResources(inspectorClient, managedResourcesState);
-  const { resourceTemplates, refresh: refreshResourceTemplates } =
-    useManagedResourceTemplates(inspectorClient, managedResourceTemplatesState);
+  const {
+    resourceTemplates,
+    error: resourceTemplatesLoadError,
+    refresh: refreshResourceTemplates,
+  } = useManagedResourceTemplates(
+    inspectorClient,
+    managedResourceTemplatesState,
+  );
   // Paged (paginated) list sources. When `paginatedLists` is on the managed
   // states skip their all-page walk and these drive the sidebar instead (#1721).
   const {
@@ -4373,6 +4382,9 @@ function App() {
           toolsListChanged={toolsListChanged}
           promptsListChanged={promptsListChanged}
           resourcesListChanged={resourcesListChanged}
+          toolsLoadError={toolsLoadError}
+          promptsLoadError={promptsLoadError}
+          resourcesLoadError={resourcesLoadError ?? resourceTemplatesLoadError}
           subscriptions={subscriptions}
           subscriptionStreamState={subscriptionStreamState}
           logs={logs}