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

lib/ratelimit.ts

@@ -0,0 +1,27 @@
+import { isProductionEnvironment } from "@/lib/constants";
+import { ChatbotError } from "@/lib/errors";
+
+const MAX_MESSAGES = 30;
+const TTL_MS = 60 * 60 * 1000;
+
+const ipCounts = new Map<string, { count: number; resetAt: number }>();
+
+export async function checkIpRateLimit(ip: string | undefined) {
+  if (!isProductionEnvironment || !ip) {
+    return;
+  }
+
+  const now = Date.now();
+  const entry = ipCounts.get(ip);
+
+  if (!entry || entry.resetAt < now) {
+    ipCounts.set(ip, { count: 1, resetAt: now + TTL_MS });
+    return;
+  }
+
+  entry.count += 1;
+
+  if (entry.count > MAX_MESSAGES) {
+    throw new ChatbotError("rate_limit:chat");
+  }
+}