fix: trigger docs workflow when lockfile changes

docs:build uses npm ci; include package.json and package-lock.json in paths.

.github/workflows/docs.yml

@@ -7,6 +7,8 @@ on:
       - 'docs-site/**'
       - 'docs/screenshots/**'
       - '.github/workflows/docs.yml'
+      - 'package.json'
+      - 'package-lock.json'
   workflow_dispatch:
 
 permissions: