Analyzer安定化完了: NYASH_DISABLE_PLUGINS=1復元 + plugin無効化根治

## 修正内容
1. **hako_check.sh/run_tests.sh**: NYASH_DISABLE_PLUGINS=1 + NYASH_BOX_FACTORY_POLICY=builtin_first追加
2. **src/box_factory/plugin.rs**: NYASH_DISABLE_PLUGINS=1チェック追加
3. **src/box_factory/mod.rs**: plugin shortcut pathでNYASH_DISABLE_PLUGINS尊重
4. **tools/hako_check/render/graphviz.hako**: smart quotes修正（parse error解消）

## 根本原因
- NYASH_USE_PLUGIN_BUILTINS=1が自動設定され、ArrayBox/MapBoxがplugin経由で生成を試行
- bid/registry.rsで"Plugin loading temporarily disabled"の状態でも試行されエラー
- mod.rs:272のshortcut pathがNYASH_DISABLE_PLUGINSを無視していた

## テスト結果
- 10/11 PASS（HC011,13-18,21-22,31）
- HC012: 既存issue（JSON安定化未完）

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

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

lang/src/shared/common/string_helpers.hako

@@ -1,4 +1,4 @@
-// string_helpers.hako — StringHelpers (common, pure helpers)
+// string_helpers.hako - StringHelpers (common, pure helpers)
 // Responsibility: numeric/string conversions and JSON quoting for selfhost tools.
 // Non-responsibility: JSON scanning beyond local character processing; use CfgNavigatorBox/StringScanBox for navigation.
 
@@ -84,9 +84,9 @@ static box StringHelpers {
     return out
   }
 
-  // ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
-  // 🆕 Extended String Utilities (added for parser/compiler unification)
-  // ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
+  // ------------------------------------
+  // NEW: Extended String Utilities (added for parser/compiler unification)
+  // ------------------------------------
 
   // Character predicates
   is_digit(ch) { return ch >= "0" && ch <= "9" }