Initial commit: EGBE chatbot template

Stripped from vercel/chatbot (Apache 2.0):
- Dropped @vercel/* packages and AI Gateway
- Removed artifacts feature (code/text/sheet/image side panel)
- Switched AI provider to @ai-sdk/openai-compatible -> EGBE LiteLLM
- Replaced Vercel Blob upload with data URLs
- Dropped Redis resumable streams and rate limiter (in-memory now)
- Added Dockerfile (Next.js standalone) + entrypoint that runs migrations
- Wired DATABASE_URL, EGBE_AI_API_URL/KEY, NEXT_PUBLIC_BASE_URL for app-deploy.sh

app/(chat)/api/messages/route.ts

@@ -0,0 +1,43 @@
+import { auth } from "@/app/(auth)/auth";
+import { getChatById, getMessagesByChatId } from "@/lib/db/queries";
+import { convertToUIMessages } from "@/lib/utils";
+
+export async function GET(request: Request) {
+  const { searchParams } = new URL(request.url);
+  const chatId = searchParams.get("chatId");
+
+  if (!chatId) {
+    return Response.json({ error: "chatId required" }, { status: 400 });
+  }
+
+  const [session, chat, messages] = await Promise.all([
+    auth(),
+    getChatById({ id: chatId }),
+    getMessagesByChatId({ id: chatId }),
+  ]);
+
+  if (!chat) {
+    return Response.json({
+      messages: [],
+      visibility: "private",
+      userId: null,
+      isReadonly: false,
+    });
+  }
+
+  if (
+    chat.visibility === "private" &&
+    (!session?.user || session.user.id !== chat.userId)
+  ) {
+    return Response.json({ error: "forbidden" }, { status: 403 });
+  }
+
+  const isReadonly = !session?.user || session.user.id !== chat.userId;
+
+  return Response.json({
+    messages: convertToUIMessages(messages),
+    visibility: chat.visibility,
+    userId: chat.userId,
+    isReadonly,
+  });
+}