fix: resolve all test failures and Cubic review issues

- Fix unstable-agent-babysitter: add promptAsync to test mock
- Fix claude-code-mcp-loader: isolate tests from user home configs
- Fix npm-dist-tags: encode packageName for scoped packages
- Fix agent-builder: clone source to prevent shared object mutation
- Fix add-plugin-to-opencode-config: handle JSONC with leading comments
- Fix auth-plugins/add-provider-config: error on parse failures
- Fix bun-install: clear timeout on completion
- Fix git-diff-stats: include untracked files in diff summary

src/cli/config-manager/add-plugin-to-opencode-config.ts

@@ -64,7 +64,7 @@ export async function addPluginToOpenCodeConfig(currentVersion: string): Promise
         const newContent = content.replace(pluginArrayRegex, `"plugin": [\n    ${formattedPlugins}\n  ]`)
         writeFileSync(path, newContent)
       } else {
-        const newContent = content.replace(/^(\s*\{)/, `$1\n  "plugin": ["${pluginEntry}"],`)
+        const newContent = content.replace(/(\{)/, `$1\n  "plugin": ["${pluginEntry}"],`)
         writeFileSync(path, newContent)
       }
     } else {