fix(share): surface the real error on the share AI widget (#87)

The widget hardcoded a generic 'Something went wrong' body and ignored
error.message, violating AGENTS.md. Render describeChatError(error.message, t) —
the same helper the internal chat uses — so a reader sees the real 402/429/503
cause instead of a bare 'try again'.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

apps/client/src/features/share/components/share-ai-widget.tsx

@@ -21,6 +21,7 @@ import { useTranslation } from "react-i18next";
 import { useChat, type UIMessage } from "@ai-sdk/react";
 import { DefaultChatTransport } from "ai";
 import MessageList from "@/features/ai-chat/components/message-list.tsx";
+import { describeChatError } from "@/features/ai-chat/utils/error-message.ts";
 
 interface ShareAiWidgetProps {
   /** The share id (or key) the assistant is scoped to. */
@@ -174,7 +175,9 @@ export default function ShareAiWidget({ shareId, pageId }: ShareAiWidgetProps) {
             mb="xs"
             title={t("Something went wrong")}
           >
-            {t("The assistant is unavailable right now. Please try again.")}
+            {/* Surface the real cause (provider/gating message) instead of a
+                generic line — same helper the internal chat uses. */}
+            {describeChatError(error.message ?? "", t)}
           </Alert>
         )}