Phase 21.2 Complete: VM Adapter正規実装 + devブリッジ完全撤去

## 🎉 Phase 21.2完全達成

### ✅ 実装完了
- VM static box 永続化（singleton infrastructure）
- devブリッジ完全撤去（adapter_dev.rs削除、by-name dispatch削除）
- .hako正規実装（MirCallV1Handler, AbiAdapterRegistry等）
- text-merge経路完全動作
- 全phase2120 adapter reps PASS（7テスト）

### 🐛 バグ修正
1. strip_local_decl修正
   - トップレベルのみlocal削除、メソッド内は保持
   - src/runner/modes/common_util/hako.rs:29

2. static box フィールド永続化
   - MirInterpreter singleton storage実装
   - me parameter binding修正（1:1マッピング）
   - getField/setField string→singleton解決
   - src/backend/mir_interpreter/{mod,exec,handlers/boxes_object_fields}.rs

3. Map.len alias rc=0修正
   - [map/missing]パターン検出でnull扱い（4箇所）
   - lang/src/vm/boxes/mir_call_v1_handler.hako:91-93,131-133,151-153,199-201

### 📁 主要変更ファイル

#### Rust（VM Runtime）
- src/backend/mir_interpreter/mod.rs - static box singleton storage
- src/backend/mir_interpreter/exec.rs - parameter binding fix
- src/backend/mir_interpreter/handlers/boxes_object_fields.rs - singleton resolution
- src/backend/mir_interpreter/handlers/calls.rs - dev bridge removal
- src/backend/mir_interpreter/utils/mod.rs - adapter_dev module removal
- src/backend/mir_interpreter/utils/adapter_dev.rs - DELETED (7555 bytes)
- src/runner/modes/vm.rs - static box declaration collection
- src/runner/modes/common_util/hako.rs - strip_local_decl fix
- src/instance_v2.rs - Clone implementation

#### Hako (.hako実装)
- lang/src/vm/boxes/mir_call_v1_handler.hako - [map/missing] detection
- lang/src/vm/boxes/abi_adapter_registry.hako - NEW (adapter registry)
- lang/src/vm/helpers/method_alias_policy.hako - method alias support

#### テスト
- tools/smokes/v2/profiles/quick/core/phase2120/s3_vm_adapter_*.sh - 7 new tests

### 🎯 テスト結果
```
✅ s3_vm_adapter_array_len_canary_vm.sh
✅ s3_vm_adapter_array_len_per_recv_canary_vm.sh
✅ s3_vm_adapter_array_length_alias_canary_vm.sh
✅ s3_vm_adapter_array_size_alias_canary_vm.sh
✅ s3_vm_adapter_map_len_alias_state_canary_vm.sh
✅ s3_vm_adapter_map_length_alias_state_canary_vm.sh
✅ s3_vm_adapter_map_size_struct_canary_vm.sh
```

環境フラグ: HAKO_ABI_ADAPTER=1 HAKO_ABI_ADAPTER_DEV=0

### 🏆 設計品質
- ✅ ハードコード禁止（AGENTS.md 5.1）完全準拠
- ✅ 構造的・一般化設計（特定Box名のif分岐なし）
- ✅ 後方互換性保持（既存コード破壊ゼロ）
- ✅ text-merge経路（.hako依存関係正しくマージ）

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

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

src/runner/modes/common_util/hako.rs

@@ -14,9 +14,30 @@ pub fn looks_like_hako_code(s: &str) -> bool {
 }
 
 /// Remove leading `local ` declarations at line head to keep Nyash parser stable
+/// Conservative: only when line-head token is exactly `local` followed by a space.
+/// Phase 21.2 fix: ONLY strip truly top-level `local` (zero indentation).
+/// Keep `local` inside blocks (indented lines) to preserve Nyash variable declaration semantics.
 pub fn strip_local_decl(s: &str) -> String {
-    // Stage‑3 パーサでは 'local' を受理できるため、変換は行わず原文を返す
-    s.to_string()
+    let mut out = String::with_capacity(s.len());
+    for line in s.lines() {
+        let bytes = line.as_bytes();
+        let mut i = 0;
+        while i < bytes.len() && (bytes[i] == b' ' || bytes[i] == b'\t') { i += 1; }
+        let mut stripped = false;
+        // Only strip `local ` if it's at the very beginning (i == 0)
+        // Keep `local ` inside blocks (i > 0) to preserve variable declarations
+        if i == 0 && i + 6 <= bytes.len() && &bytes[i..i+6] == b"local " {
+            out.push_str(&line[..i]);
+            out.push_str(&line[i+6..]);
+            out.push('\n');
+            stripped = true;
+        }
+        if !stripped {
+            out.push_str(line);
+            out.push('\n');
+        }
+    }
+    out
 }
 
 /// Policy toggle: fail fast when Hako-like code enters Nyash VM path

src/runner/modes/common_util/resolve/strip.rs

@@ -516,15 +516,18 @@ pub fn parse_preludes_to_asts(
             .map_err(|e| format!("using: error reading {}: {}", prelude_path, e))?;
         let (clean_src, _nested) = collect_using_and_strip(runner, &src, prelude_path)?;
 
-        // Safety valve: do not attempt to parse .hako preludes as Nyash AST.
-        // Hako は別言語系のため、プレリュード統合はテキスト統合に一本化する。
+        // IMPORTANT: Do not attempt to AST-parse .hako preludes here.
+        // .hako is Hakorune surface, not Nyash AST. VM/VM-fallback paths
+        // will route to text-merge when any prelude is .hako.
         if prelude_path.ends_with(".hako") {
             if debug {
-                eprintln!("[strip-debug] Skipping AST parse for Hako prelude: {} (use text merge)", prelude_path);
+                eprintln!("[strip-debug] skip AST parse for .hako prelude: {}", prelude_path);
             }
             continue;
         }
 
+        let clean_src = clean_src;
+
         // Debug: dump clean_src if NYASH_STRIP_DEBUG=1
         if debug {
             eprintln!("[strip-debug] [{}/{}] About to parse: {}", idx + 1, prelude_paths.len(), prelude_path);
@@ -756,7 +759,15 @@ pub fn merge_prelude_text(
 
         // Strip using lines from prelude and normalize
         let (cleaned_raw, _nested) = collect_using_and_strip(runner, &content, path)?;
-        let cleaned = normalize_text_for_inline(&cleaned_raw);
+        let mut cleaned = normalize_text_for_inline(&cleaned_raw);
+        // Hako-friendly normalize for preludes: always strip leading `local ` at line head
+        // when the prelude is a .hako (or looks like Hako code). This prevents top-level
+        // `local` from tripping the Nyash parser after text merge.
+        if path.ends_with(".hako")
+            || crate::runner::modes::common_util::hako::looks_like_hako_code(&cleaned)
+        {
+            cleaned = crate::runner::modes::common_util::hako::strip_local_decl(&cleaned);
+        }
 
         if trace {
             crate::runner::trace::log(format!(
@@ -777,7 +788,14 @@ pub fn merge_prelude_text(
     }
 
     // Add main source (already cleaned of using lines) and normalize
-    let cleaned_main_norm = normalize_text_for_inline(&cleaned_main);
+    let mut cleaned_main_norm = normalize_text_for_inline(&cleaned_main);
+    // Hako-friendly normalize for main: always strip leading `local ` at line head
+    // when the merged main looks like Hako code (or file is .hako as a heuristic).
+    if filename.ends_with(".hako")
+        || crate::runner::modes::common_util::hako::looks_like_hako_code(&cleaned_main_norm)
+    {
+        cleaned_main_norm = crate::runner::modes::common_util::hako::strip_local_decl(&cleaned_main_norm);
+    }
     merged.push_str(&cleaned_main_norm);
 
     if trace {
@@ -789,6 +807,13 @@ pub fn merge_prelude_text(
         ));
     }
 
+    // Optional dump of merged text for diagnostics
+    if let Ok(dump_path) = std::env::var("NYASH_RESOLVE_DUMP_MERGED") {
+        if !dump_path.is_empty() {
+            let _ = std::fs::write(&dump_path, &merged);
+        }
+    }
+
     Ok(normalize_text_for_inline(&merged))
 }