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

package.json

@@ -1,6 +1,6 @@
 {
   "name": "md2html",
-  "version": "1.0.0",
+  "version": "1.0.2",
   "description": "",
   "main": "index.js",
   "scripts": {