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

scripts/sync-version-plugin.cjs

@@ -0,0 +1,41 @@
+/**
+ * semantic-release plugin to sync VERSION file
+ *
+ * semantic-release updates package.json but not the VERSION file.
+ * This plugin keeps VERSION in sync for shell scripts and installers.
+ */
+const fs = require('fs');
+const path = require('path');
+
+module.exports = {
+  /**
+   * Called during the prepare step before git commit
+   */
+  prepare(_pluginConfig, context) {
+    const { nextRelease, logger } = context;
+    const versionFile = path.join(process.cwd(), 'VERSION');
+
+    // Write version without 'v' prefix (e.g., "5.1.0" not "v5.1.0")
+    const version = nextRelease.version;
+    fs.writeFileSync(versionFile, version + '\n');
+    logger.log('[sync-version-plugin] Updated VERSION file to %s', version);
+
+    // Also update installers for standalone installs
+    const installSh = path.join(process.cwd(), 'installers', 'install.sh');
+    const installPs1 = path.join(process.cwd(), 'installers', 'install.ps1');
+
+    if (fs.existsSync(installSh)) {
+      let content = fs.readFileSync(installSh, 'utf8');
+      content = content.replace(/^CCS_VERSION=".*"/m, `CCS_VERSION="${version}"`);
+      fs.writeFileSync(installSh, content);
+      logger.log('[sync-version-plugin] Updated installers/install.sh');
+    }
+
+    if (fs.existsSync(installPs1)) {
+      let content = fs.readFileSync(installPs1, 'utf8');
+      content = content.replace(/^\$CcsVersion = ".*"/m, `$CcsVersion = "${version}"`);
+      fs.writeFileSync(installPs1, content);
+      logger.log('[sync-version-plugin] Updated installers/install.ps1');
+    }
+  }
+};