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/chat/schema.ts

@@ -0,0 +1,37 @@
+import { z } from "zod";
+
+const textPartSchema = z.object({
+  type: z.enum(["text"]),
+  text: z.string().min(1).max(2000),
+});
+
+const filePartSchema = z.object({
+  type: z.enum(["file"]),
+  mediaType: z.enum(["image/jpeg", "image/png", "image/webp", "image/gif"]),
+  name: z.string().min(1).max(100),
+  url: z.string(),
+});
+
+const partSchema = z.union([textPartSchema, filePartSchema]);
+
+const userMessageSchema = z.object({
+  id: z.string().uuid(),
+  role: z.enum(["user"]),
+  parts: z.array(partSchema),
+});
+
+const toolApprovalMessageSchema = z.object({
+  id: z.string(),
+  role: z.enum(["user", "assistant"]),
+  parts: z.array(z.record(z.unknown())),
+});
+
+export const postRequestBodySchema = z.object({
+  id: z.string().uuid(),
+  message: userMessageSchema.optional(),
+  messages: z.array(toolApprovalMessageSchema).optional(),
+  selectedChatModel: z.string(),
+  selectedVisibilityType: z.enum(["public", "private"]),
+});
+
+export type PostRequestBody = z.infer<typeof postRequestBodySchema>;