Use remote Chromium container instead of local Puppeteer launch

- Add browserless/chromium container to docker-compose
- Add docker-compose.dev.yml for local dev (Chromium on port 3001)
- Browser scraper connects via WebSocket (CHROMIUM_WS env var)
- Falls back to local launch if CHROMIUM_WS not set
- Remove Chromium install from Dockerfile (smaller image)
- Auto-reconnect on browser disconnect

Tested: remote Chromium connects in ~500ms, HG Spot scrapes in
~2.2s total. No longer blocks the Node.js event loop.

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

docker-compose.dev.yml

@@ -0,0 +1,9 @@
+services:
+  chromium:
+    image: ghcr.io/browserless/chromium
+    ports:
+      - "3001:3000"
+    environment:
+      - MAX_CONCURRENT_SESSIONS=5
+      - CONNECTION_TIMEOUT=30000
+    restart: unless-stopped