Lazy-load puppeteer to fix tsx watch hanging on startup

Puppeteer import at top level was blocking tsx watch mode,
preventing the server from starting. Now imported dynamically
only when a JS-rendered store is actually scraped.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/server/scraper/browser-scraper.ts

@@ -1,4 +1,4 @@
-import puppeteer, { type Browser } from 'puppeteer';
+import type { Browser } from 'puppeteer';
 import type { Store } from '../models/store.js';
 import type { ScrapedItem } from './result-parser.js';
 
@@ -10,7 +10,8 @@ const NAVIGATION_TIMEOUT = 20_000;
 async function getBrowser(): Promise<Browser> {
   if (browser && browser.connected) return browser;
 
-  browser = await puppeteer.launch({
+  const puppeteer = await import('puppeteer');
+  browser = await puppeteer.default.launch({
     headless: true,
     args: [
       '--no-sandbox',