Update CI to test on Node 20.x and 22.x

- Remove Node 16.x (EOL) and 18.x from test matrix
- Add Node 22.x (latest LTS)
- Focus on current and next LTS versions for build tooling compatibility

Author: claude

.github/workflows/build.yml

@@ -15,7 +15,7 @@ jobs:
 
     strategy:
       matrix:
-        node-version: [16.x, 18.x, 20.x]
+        node-version: [20.x, 22.x]
         # See supported Node.js release schedule at https://nodejs.org/en/about/releases/
 
     steps: