feat(daemon): implement content routes for screenshot/text/html retrieval (Task 9)

- Add contentRoutes handler factory in routes/content.ts
- GET /pages/:id/screenshot returns PNG as base64
- GET /pages/:id/text returns document.body.innerText
- GET /pages/:id/html returns document.documentElement.outerHTML
- All use safeStringify, 404 on PAGE_NOT_FOUND
- Register contentRoutes in server.ts
- Add 8 integration tests with mock BrowserManager

packages/daemon/src/server.ts

@@ -1,12 +1,14 @@
 import http from 'node:http';
 import { healthRoute } from './routes/health.js';
 import { pageRoutes } from './routes/pages.js';
+import { contentRoutes } from './routes/content.js';
 import type { BrowserManager } from './browser-manager.js';
 
 export function startServer(port: number, browserManager?: BrowserManager): Promise<http.Server> {
   const routes = [healthRoute];
   if (browserManager) {
     routes.push(pageRoutes(browserManager));
+    routes.push(contentRoutes(browserManager));
   }
 
   return new Promise((resolve) => {