fix(chat): skip CSRF for guest endpoint

apps/api/src/chat-proxy/chat-proxy.controller.ts

@@ -1,6 +1,7 @@
 import { Body, Controller, HttpException, Logger, Post, Req, Res, UseGuards } from "@nestjs/common";
 import type { Response } from "express";
 import { AuthGuard } from "../auth/guards/auth.guard";
+import { SkipCsrf } from "../common/decorators/skip-csrf.decorator";
 import type { MaybeAuthenticatedRequest } from "../auth/types/better-auth-request.interface";
 import { ChatStreamDto } from "./chat-proxy.dto";
 import { ChatProxyService } from "./chat-proxy.service";
@@ -14,6 +15,7 @@ export class ChatProxyController {
   // POST /api/chat/guest
   // Guest chat endpoint - no authentication required
   // Uses a shared LLM configuration for unauthenticated users
+  @SkipCsrf()
   @Post("guest")
   async guestChat(
     @Body() body: ChatStreamDto,