fix: salvage a list result's valid entries when one is malformed (#1909)

The SDK validates a list result as a whole, so a single non-conforming entry
rejected the entire response and the panel showed "Couldn't load resources"
with zero items — the exact opposite of what a debugging tool should do with a
server that is 90% right. Reported against a PHP server whose empty
`annotations` object reaches the wire as `[]` rather than `{}`.

`listAll*` now falls back to a lenient re-walk when — and only when — the SDK
rejects a result it received (`InvalidResult` / `UnsupportedResultType`), keeps
the entries that validate, and reports the rest. A conforming server takes the
strict, cache-aware path exactly as before.

Salvaging is not accepting: the dropped entries are named with their reason in
a warning above the list, and the Protocol entry is still marked rejected, so
the wire truth survives. When every entry validates, the original error is
rethrown rather than swallowed — the rejection was about something the
per-item pass cannot explain.

`isClientDecodeRejection` moves to the new module and is now shared with
managedListState, which had the only copy.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HDdo1rNRVQnVRRdsqSrvG3
Signed-off-by: cliffhall <cliff@futurescale.com>

clients/web/src/components/screens/PromptsScreen/PromptsScreen.tsx

@@ -8,6 +8,7 @@ import {
   Stack,
   Text,
 } from "@mantine/core";
+import type { MalformedListItem } from "@inspector/core/mcp";
 import type { GetPromptResult, Prompt } from "@modelcontextprotocol/client";
 import { PromptControls } from "../../groups/PromptControls/PromptControls";
 import type { ListPaginationControlsProps } from "../../elements/ListPaginationControls/ListPaginationControls";
@@ -34,6 +35,11 @@ export interface PromptsScreenProps {
   onUiChange: (next: PromptsUiState) => void;
   onRefreshList: () => void;
   /** A failed list load, rendered above the sidebar list (#1953). */
+  /**
+   * Entries dropped from this screen's list result(s) as malformed; the list
+   * panel warns about them above the list (#1909).
+   */
+  malformedListItems?: MalformedListItem[];
   loadError?: Error | null;
   /** Pagination controls rendered in the sidebar (#1721). */
   pagination: ListPaginationControlsProps;
@@ -138,6 +144,7 @@ export function PromptsScreen({
   completionsSupported,
   onUiChange,
   onRefreshList,
+  malformedListItems,
   loadError,
   pagination,
   onGetPrompt,
@@ -277,6 +284,7 @@ export function PromptsScreen({
             listChanged={listChanged}
             onRefreshList={onRefreshList}
             loadError={loadError}
+            malformedListItems={malformedListItems}
             pagination={pagination}
             onSearchChange={(value) => onUiChange({ ...ui, search: value })}
             onSelectPrompt={handleSelectPrompt}