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>

src/backend/mir_interpreter/mod.rs

@@ -166,9 +166,23 @@ impl MirInterpreter {
         let ret = if func.signature.params.len() == 0 {
             self.execute_function(func)?
         } else {
-            // Build argv from NYASH_SCRIPT_ARGS_JSON (set by CLI when using `--`) or NYASH_ARGV (JSON array)
+            // Build argv from (priority) HEX JSON, normal JSON, or NYASH_ARGV
+            // 1) NYASH_SCRIPT_ARGS_HEX_JSON: JSON array of hex-encoded UTF-8 strings
+            // 2) NYASH_SCRIPT_ARGS_JSON: JSON array of strings
+            // 3) NYASH_ARGV: JSON array (legacy)
             let mut argv_list: Vec<String> = Vec::new();
-            if let Ok(s) = std::env::var("NYASH_SCRIPT_ARGS_JSON") {
+            if let Ok(s) = std::env::var("NYASH_SCRIPT_ARGS_HEX_JSON") {
+                if let Ok(v) = serde_json::from_str::<Vec<String>>(&s) {
+                    let mut out = Vec::with_capacity(v.len());
+                    for hx in v.into_iter() {
+                        match hex_decode_to_string(&hx) {
+                            Ok(ss) => out.push(ss),
+                            Err(_) => out.push(String::new()),
+                        }
+                    }
+                    argv_list = out;
+                }
+            } else if let Ok(s) = std::env::var("NYASH_SCRIPT_ARGS_JSON") {
                 if let Ok(v) = serde_json::from_str::<Vec<String>>(&s) { argv_list = v; }
             } else if let Ok(s) = std::env::var("NYASH_ARGV") {
                 if let Ok(v) = serde_json::from_str::<Vec<String>>(&s) { argv_list = v; }
@@ -196,3 +210,26 @@ impl MirInterpreter {
         self.exec_function_inner(func, None)
     }
 }
+
+fn hex_decode_to_string(hex: &str) -> Result<String, ()> {
+    let mut bytes: Vec<u8> = Vec::with_capacity(hex.len() / 2);
+    let mut it = hex.as_bytes().iter().cloned();
+    while let (Some(h), Some(l)) = (it.next(), it.next()) {
+        let hi = from_hex(h).ok_or(())?;
+        let lo = from_hex(l).ok_or(())?;
+        bytes.push((hi << 4) | lo);
+    }
+    match String::from_utf8(bytes) {
+        Ok(s) => Ok(s),
+        Err(e) => Ok(String::from_utf8_lossy(e.as_bytes()).into_owned()),
+    }
+}
+
+fn from_hex(b: u8) -> Option<u8> {
+    match b {
+        b'0'..=b'9' => Some(b - b'0'),
+        b'a'..=b'f' => Some(b - b'a' + 10),
+        b'A'..=b'F' => Some(b - b'A' + 10),
+        _ => None,
+    }
+}