feat(release): implement semantic versioning automation with conventional commits

- Add semantic-release for automated npm publishing
- Add commitlint + husky for commit message enforcement
- Add professional branching strategy (beta → main workflow)
- Create .releaserc.json with multi-branch config
- Create sync-version-plugin.cjs for VERSION file sync
- Update release.yml workflow (Node.js 22 required)
- Update CLAUDE.md and CONTRIBUTING.md with new workflow
- Deprecate manual bump-version.sh script

commitlint.config.cjs

@@ -0,0 +1,25 @@
+// Commitlint configuration for conventional commits
+// See: https://commitlint.js.org/
+module.exports = {
+  extends: ['@commitlint/config-conventional'],
+  rules: {
+    // Allowed commit types (determines version bump)
+    'type-enum': [2, 'always', [
+      'feat',     // New feature → MINOR
+      'fix',      // Bug fix → PATCH
+      'docs',     // Documentation only → no release
+      'style',    // Formatting, no code change → no release
+      'refactor', // Code change, no feat/fix → no release
+      'perf',     // Performance improvement → PATCH
+      'test',     // Adding tests → no release
+      'chore',    // Maintenance → no release
+      'ci',       // CI/CD changes → no release
+      'build',    // Build system → no release
+      'revert'    // Revert commit → PATCH
+    ]],
+    // Subject must be lowercase
+    'subject-case': [2, 'always', 'lower-case'],
+    // Max header length (type + scope + subject)
+    'header-max-length': [2, 'always', 100]
+  }
+};