Phase 21.3 WIP: Hako Source Checker improvements - HC011/HC016/HC017 実装完了

主な変更:
- ✅ HC011 (dead methods) 実装・テスト緑
- ✅ HC016 (unused alias) 実装・テスト緑
- ✅ HC017 (non-ascii quotes) 実装完了
- 🔧 tokenizer/parser_core 強化（AST優先ルート）
- 🛡️ plugin_guard.rs 追加（stderr専用出力）
- 📋 テストインフラ整備（run_tests.sh改善）

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

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

src/runner/modes/common_util/mod.rs

@@ -12,3 +12,4 @@ pub mod resolve;
 pub mod exec;
 pub mod core_bridge;
 pub mod hako;
+pub mod plugin_guard;

src/runner/modes/common_util/plugin_guard.rs

@@ -0,0 +1,89 @@
+/*!
+ * Plugin guard utilities
+ *
+ * Centralized helper to check required plugin providers and emit
+ * consistent diagnostics across runner modes.
+ */
+
+/// Build the list of required provider type names.
+///
+/// Priority:
+/// - If env `NYASH_PLUGIN_OVERRIDE_TYPES` is set, use it (comma-separated).
+/// - Otherwise, return a conservative default set used in VM paths.
+pub fn gather_required_providers() -> Vec<String> {
+    if let Ok(list) = std::env::var("NYASH_PLUGIN_OVERRIDE_TYPES") {
+        let mut v: Vec<String> = list
+            .split(',')
+            .map(|s| s.trim().to_string())
+            .filter(|s| !s.is_empty())
+            .collect();
+        v.sort();
+        v.dedup();
+        return v;
+    }
+    // Default conservative set
+    let mut v = vec![
+        "FileBox".to_string(),
+        "ConsoleBox".to_string(),
+        "ArrayBox".to_string(),
+        "MapBox".to_string(),
+        "StringBox".to_string(),
+        "IntegerBox".to_string(),
+    ];
+    v
+}
+
+/// Return missing providers by checking the unified registry.
+pub fn detect_missing_providers(required: &[String]) -> Vec<String> {
+    let reg = nyash_rust::runtime::get_global_registry();
+    let mut missing: Vec<String> = Vec::new();
+    for t in required {
+        if reg.get_provider(t).is_none() {
+            missing.push(t.clone());
+        }
+    }
+    missing
+}
+
+/// Emit hints for specific provider types.
+fn emit_hints_for(missing: &[String]) {
+    if missing.iter().any(|t| t == "FileBox") {
+        eprintln!("[plugin/hint] FileBox plugin is required for file I/O (new FileBox/open/read).");
+        eprintln!("[plugin/hint] Build and load plugin: see tools/plugin_v2_smoke.sh or configure nyash.toml [libraries.*.FileBox].");
+        eprintln!("[plugin/hint] Ensure LD_LIBRARY_PATH (or platform equivalent) includes the plugin directory.");
+        eprintln!("[plugin/hint] For analyzer runs, you can avoid FileBox via --source-file <path> <text>.");
+    }
+}
+
+/// Check provider availability and emit diagnostics.
+///
+/// - `strict`: exit(1) when any provider is missing.
+/// - `quiet_pipe`: respect quiet JSON pipelines; we still write diagnostics to stderr only.
+/// - `label`: context label (e.g., "vm", "vm-fallback") for messages.
+pub fn check_and_report(strict: bool, quiet_pipe: bool, label: &str) {
+    let required = gather_required_providers();
+    let missing = detect_missing_providers(&required);
+    if missing.is_empty() {
+        return;
+    }
+
+    if strict {
+        eprintln!(
+            "❌ {} plugin-first strict: missing providers for: {:?}",
+            label, missing
+        );
+        emit_hints_for(&missing);
+        // Do not print anything to stdout in quiet mode; just exit with 1
+        std::process::exit(1);
+    } else {
+        eprintln!(
+            "[plugin/missing] {} providers not loaded: {:?}",
+            label, missing
+        );
+        emit_hints_for(&missing);
+        if quiet_pipe {
+            // In quiet JSON mode, avoid noisy stdout; hints are on stderr already.
+        }
+    }
+}
+