fix: prevent Chromium zombie leak in htmlToPdf

- Wrap browser lifecycle in try/finally so browser.close() always runs
- Fall back to SIGKILL of browser.process() if close() fails
- Add --disable-dev-shm-usage to launch args (container stability)
- Add tini as ENTRYPOINT in Dockerfile for defense in depth
- Bump version to 1.0.2

Dockerfile

@@ -4,6 +4,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
     chromium \
     fonts-freefont-ttf \
     fonts-noto-cjk \
+    tini \
     && rm -rf /var/lib/apt/lists/*
 
 WORKDIR /app
@@ -21,4 +22,5 @@ EXPOSE 3000
 HEALTHCHECK --interval=30s --timeout=5s --retries=3 \
   CMD node -e "require('http').get('http://localhost:3000/health', r => process.exit(r.statusCode === 200 ? 0 : 1))"
 
+ENTRYPOINT ["/usr/bin/tini", "--"]
 CMD ["node", "server.js"]