Update build (#354)

- yarn-test.yml: Change push trigger from 'main' to 'master' to match
  actual default branch; add build steps; drop EOL Node 18
- package.json: Add 'lint' script for eslint

---------

Co-authored-by: james-enperso <james@enperso.com>
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: 3 people

.github/workflows/yarn-test.yml

@@ -4,7 +4,7 @@ on:
   workflow_dispatch:
   push:
     branches:
-      - main
+      - master
   pull_request:
 
 permissions:
@@ -17,7 +17,7 @@ jobs:
     strategy:
       matrix:
         # build against all active LTS and current stable node; include "latest" for early signal as a required job
-        node-version: [18.x, 20.x, 22.x, 24.x, latest]
+        node-version: [20.x, 22.x, 24.x, latest]
 
     steps:
       - uses: actions/checkout@v6
@@ -28,5 +28,7 @@ jobs:
           cache: npm
       - name: Install dependencies
         run: npm ci
+      - name: Build
+        run: npm run build
       - name: Run tests
         run: npm test

package.json

@@ -14,6 +14,7 @@
   },
   "scripts": {
     "build": "tsup",
+    "lint": "eslint .",
     "test": "jest"
   },
   "engines": {