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

components/theme-provider.tsx

@@ -0,0 +1,8 @@
+"use client";
+
+import { ThemeProvider as NextThemesProvider } from "next-themes";
+import type { ThemeProviderProps } from "next-themes/dist/types";
+
+export function ThemeProvider({ children, ...props }: ThemeProviderProps) {
+  return <NextThemesProvider {...props}>{children}</NextThemesProvider>;
+}