fix docker build for vendored page agent

Dockerfile

@@ -2,6 +2,7 @@ FROM node:22-alpine AS builder
 WORKDIR /app
 
 COPY package*.json ./
+COPY vendor/page-agent ./vendor/page-agent
 RUN npm ci
 
 COPY . .

src/lib/page-agent.ts

@@ -17,7 +17,7 @@ function createPageAgent() {
 
 ${adminGuide}`
     },
-  customFetch: (input, init) => {
+    customFetch: (input: RequestInfo | URL, init?: RequestInit) => {
       const token = localStorage.getItem('studio-admin-token');
       return fetch(input, {
         ...init,