ci: add semantic-release config, regenerate build icons, normalize Node 20

- Create .releaserc.json with conventional commits, changelog, npm version bump, and GitHub release
- Regenerate all build icons (PNG, ICO, ICNS) from new GN logo
- Normalize Node.js version to 20 across all CI workflows (testing, lint, format, release)

.github/workflows/lint.yaml

@@ -19,7 +19,7 @@ jobs:
       - name: Setup Node.js
         uses: actions/setup-node@v4
         with:
-          node-version: 22
+          node-version: 20
           cache: 'npm'
 
       - name: Install dependencies