chore: convert commitlint config to ESM, fix review issues

- Replace commitlint.config.cjs and commitlint.rules.cjs with ESM .js equivalents
- Add engines field (node >=22) to package.json
- Fix typo in action-message.js (extra space in rules_not_found message)
- Remove dead eslint-disable comment in lint-pr.js
- Remove empty TODO test in lint-pr.spec.js

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: Patrick Heneise

commitlint.config.cjs

@@ -0,0 +1,3 @@
+export default {
+  extends: ['@commitlint/config-conventional', './commitlint.rules.js']
+}

commitlint.config.js

@@ -0,0 +1,5 @@
+export default {
+  rules: {
+    'subject-case': [2, 'never', ['start-case', 'pascal-case', 'upper-case']]
+  }
+}

commitlint.rules.cjs

@@ -18,6 +18,9 @@
     "Patrick Heneise <https://patrickheneise.com>"
   ],
   "main": "src/main.js",
+  "engines": {
+    "node": ">=22"
+  },
   "scripts": {
     "check": "opensource-check --path ./",
     "prepare": "ncc build src/main.js -o dist --source-map --license licenses.txt",

commitlint.rules.js

@@ -16,7 +16,7 @@ export default {
       checkout:
         'ACTION(commitlintRulesPath): actions/checkout@v2 is required to load your commitlint rules file',
       rules_not_found:
-        'ACTION(commitlintRules ): rules module not found, using default @commitlint/config-conventional lint rules...'
+        'ACTION(commitlintRules): rules module not found, using default @commitlint/config-conventional lint rules...'
     }
   }
 }

package.json

@@ -19,7 +19,6 @@ export async function lintPR() {
   }
 
   const {
-    // eslint-disable-next-line camelcase
     number: pull_number,
     base: {
       user: { login: owner },

src/action-message.js

@@ -92,10 +92,6 @@ describe('lintPR', () => {
     assert.strictEqual(mockCore.setFailed.mock.callCount(), 0)
   })
 
-  it('fails when contextual pull request is not found', async () => {
-    // TODO: contextual pull request test
-  })
-
   it('skips linting for dependabot PRs', async () => {
     pullsGetResponse = {
       data: { ...prFixture, title: 'bump lodash from 4.0.0 to 4.1.0', user: { login: 'dependabot[bot]' } }