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/ai/providers.ts

@@ -0,0 +1,36 @@
+import { createOpenAICompatible } from "@ai-sdk/openai-compatible";
+import { customProvider } from "ai";
+import { isTestEnvironment } from "../constants";
+import { titleModel } from "./models";
+
+const litellm = createOpenAICompatible({
+  name: "egbe-litellm",
+  baseURL: process.env.EGBE_AI_API_URL ?? "https://proxy.gcp.egbe.dev/v1",
+  apiKey: process.env.EGBE_AI_API_KEY ?? "",
+});
+
+export const myProvider = isTestEnvironment
+  ? (() => {
+      const { chatModel, titleModel: mockTitle } = require("./models.mock");
+      return customProvider({
+        languageModels: {
+          "chat-model": chatModel,
+          "title-model": mockTitle,
+        },
+      });
+    })()
+  : null;
+
+export function getLanguageModel(modelId: string) {
+  if (isTestEnvironment && myProvider) {
+    return myProvider.languageModel(modelId);
+  }
+  return litellm.chatModel(modelId);
+}
+
+export function getTitleModel() {
+  if (isTestEnvironment && myProvider) {
+    return myProvider.languageModel("title-model");
+  }
+  return litellm.chatModel(titleModel.id);
+}