fix: Add Chromium to Docker for PDF certificate generation

- Install chromium in Alpine Dockerfile
- Add PUPPETEER_EXECUTABLE_PATH env var support
- Fallback to system Chrome paths if bundled Chrome not found

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Dockerfile

@@ -8,6 +8,11 @@ COPY package*.json ./
 # Inštalácia závislostí (len produkčné)
 RUN npm ci --only=production
 
+# Inštalácia Chromium pre generovanie PDF certifikátov
+RUN apk add --no-cache chromium
+ENV PUPPETEER_EXECUTABLE_PATH=/usr/bin/chromium-browser
+ENV PUPPETEER_SKIP_CHROMIUM_DOWNLOAD=true
+
 # Kopírovanie zdrojového kódu
 COPY src ./src
 COPY drizzle.config.js ./