feat: Add VM statistics and fix compilation errors for plugin tests

- Add VM instruction statistics (--vm-stats, --vm-stats-json)
- Fix missing fields in ast.rs test code (public_fields, private_fields)
- Add CliConfig fields for VM statistics
- Enable TLV debug logging in plugin_loader_v2
- Successfully test FileBox handle passing and HTTP plugin creation

🤖 Generated with [Claude Code](https://claude.ai/code)

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

docs/guides/getting-started.md

@@ -238,6 +238,20 @@ print("(3 * 4) + (20 / 4) = " + complex1)
 calc.showHistory()
 ```
 
+## 📊 VM性能計測（オプション）
+
+VMバックエンドの命令統計を有効化すると、性能分析に役立つ集計が得られます。
+
+```bash
+# 人間向け表示
+nyash --backend vm --vm-stats hello.nyash
+
+# JSON出力（ツール連携向け）
+nyash --backend vm --vm-stats --vm-stats-json hello.nyash
+```
+
+環境変数での制御も可能です（`NYASH_VM_STATS`, `NYASH_VM_STATS_JSON`）。
+
 ## ⚡ 並行処理の実践
 
 ```nyash
@@ -544,4 +558,4 @@ loop(i < 1000) {
 
 ---
 *Getting Started Guide v1.0*  
-*Everything is Box - Start Simple, Think Big*
+*Everything is Box - Start Simple, Think Big*