feat(web): red border on a server card whose connection attempt failed (#1621)

Flags the server whose last connection attempt failed with a red card
border, cleared when another server is connected or a new connection is
attempted — a persistent, at-a-glance companion to the failure toast and
the auto-opened monitoring column.

- App tracks `failedServerId`: set in onToggleConnection's non-auth
  handshake catch, cleared at the start of any new connect attempt. It is
  deliberately kept out of resetSessionScopedUiState, since the failure's
  own `disconnect` event would otherwise clear it the same tick (that same
  event clears `activeServer`, which is why the flag is tracked separately).
- New `errored` Card theme variant (red border via a new
  `--inspector-error-border` token), mirroring the `highlighted` green
  border. Precedence: disabled (dimmed) > errored > highlighted.
- Plumbed `erroredServerId` through InspectorView → ServerListScreen →
  ServerCard (`errored` prop).

Full `npm run ci` passes (validate + coverage + smoke + storybook).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BrihGWcrM9JGRyu41nzZYw

clients/web/src/components/views/InspectorView/InspectorView.tsx

@@ -347,6 +347,13 @@ export interface InspectorViewProps {
 
   // Connection state — driven by the parent via `useInspectorClient`.
   activeServer?: string;
+  /**
+   * Id of the server whose last connection attempt failed (#1621). Its card in
+   * the Servers screen draws a red border until another server is connected or
+   * a new connection is attempted. Independent of `activeServer`, which the
+   * parent clears on the failure's `disconnect` event.
+   */
+  erroredServerId?: string;
   connectionStatus: ConnectionStatus;
   initializeResult?: InitializeResult;
   latencyMs?: number;
@@ -524,6 +531,7 @@ export function InspectorView({
   servers: serversInput,
   serverListWritable = true,
   activeServer,
+  erroredServerId,
   connectionStatus,
   initializeResult,
   latencyMs,
@@ -1062,6 +1070,7 @@ export function InspectorView({
                 servers={servers}
                 writable={serverListWritable}
                 activeServer={dimCardsAgainst}
+                erroredServerId={erroredServerId}
                 onAddManually={onServerAdd}
                 onImportConfig={onServerImportConfig}
                 onImportServerJson={onServerImportJson}