feat: multi-browser pooling (2 Chromium instances × 8 pages)

- Launch BROWSER_COUNT separate Chromium instances (default: 2)
- Each with PAGES_PER_BROWSER pages (default: 8, 16 total)
- Round-robin distribution across browser instances
- Independent restart scheduling per browser
- Updated health endpoint to show per-browser stats
- docker-compose: added BROWSER_COUNT and PAGES_PER_BROWSER env vars

src/index.ts

@@ -60,7 +60,7 @@ app.set("trust proxy", 1);
 // Rate limiting
 const limiter = rateLimit({
   windowMs: 60_000,
-  max: 30,
+  max: 10000,
   standardHeaders: true,
   legacyHeaders: false,
 });