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/components/screens/ToolsScreen/ToolsScreen.tsx

@@ -60,6 +60,8 @@ export interface ToolsScreenProps {
   modernTasks?: boolean;
   onUiChange: (next: ToolsUiState) => void;
   onRefreshList: () => void;
+  /** A failed list load, rendered above the sidebar list (#1953). */
+  loadError?: Error | null;
   /** Pagination controls rendered in the sidebar (#1721). */
   pagination: ListPaginationControlsProps;
   onCallTool: (
@@ -152,6 +154,7 @@ export function ToolsScreen({
   modernTasks = false,
   onUiChange,
   onRefreshList,
+  loadError,
   pagination,
   onCallTool,
   onCancelCall,
@@ -192,6 +195,7 @@ export function ToolsScreen({
             searchText={search}
             listChanged={listChanged}
             onRefreshList={onRefreshList}
+            loadError={loadError}
             pagination={pagination}
             onSearchChange={(value) => onUiChange({ ...ui, search: value })}
             onSelectTool={handleSelectTool}