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>

Dockerfile

@@ -19,9 +19,7 @@ RUN npx tsc
 FROM node:20-alpine
 WORKDIR /app
 
-# Install Chromium for Puppeteer
-RUN apk add --no-cache chromium
-ENV PUPPETEER_EXECUTABLE_PATH=/usr/bin/chromium-browser
+# Skip Chromium download — we use a remote Chromium container
 ENV PUPPETEER_SKIP_CHROMIUM_DOWNLOAD=true
 
 COPY package*.json ./
@@ -35,6 +33,7 @@ ENV NODE_ENV=production
 ENV PORT=3000
 ENV DATABASE_PATH=/app/data/pricehunter.db
 ENV STORES_DIR=/app/stores
+ENV CHROMIUM_WS=ws://chromium:3000
 
 EXPOSE 3000
 VOLUME /app/data