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/parser/statements/modules.rs

@@ -54,32 +54,67 @@ impl NyashParser {
         })
     }
 
-    /// Parse using statement: using namespace_name
+    /// Parse using statement
+    /// Accepts forms:
+    ///  - using "module.path" (as Alias)?
+    ///  - using module.path (as Alias)?
+    /// Alias (if present) is currently ignored by the core parser and handled by runner-side resolution.
     pub(super) fn parse_using(&mut self) -> Result<ASTNode, ParseError> {
         self.advance(); // consume 'using'
 
-        // Get namespace name
-        if let TokenType::IDENTIFIER(namespace_name) = &self.current_token().token_type {
-            let name = namespace_name.clone();
-            self.advance();
-
-            // Phase 0 only allows "nyashstd"
-            if name != "nyashstd" {
-                return Err(ParseError::UnsupportedNamespace {
-                    name,
-                    line: self.current_token().line,
-                });
+        // Parse target: string literal or dotted identifiers
+        let namespace = match &self.current_token().token_type {
+            TokenType::STRING(s) => {
+                let v = s.clone();
+                self.advance();
+                v
             }
+            TokenType::IDENTIFIER(first) => {
+                let mut parts = vec![first.clone()];
+                self.advance();
+                while let TokenType::DOT = self.current_token().token_type {
+                    // consume '.' and the following IDENTIFIER
+                    self.advance();
+                    if let TokenType::IDENTIFIER(seg) = &self.current_token().token_type {
+                        parts.push(seg.clone());
+                        self.advance();
+                    } else {
+                        return Err(ParseError::UnexpectedToken {
+                            found: self.current_token().token_type.clone(),
+                            expected: "identifier after '.'".to_string(),
+                            line: self.current_token().line,
+                        });
+                    }
+                }
+                parts.join(".")
+            }
+            other => {
+                return Err(ParseError::UnexpectedToken {
+                    found: other.clone(),
+                    expected: "string or identifier".to_string(),
+                    line: self.current_token().line,
+                })
+            }
+        };
 
-            Ok(ASTNode::UsingStatement {
-                namespace_name: name,
-                span: Span::unknown(),
-            })
-        } else {
-            Err(ParseError::ExpectedIdentifier {
-                line: self.current_token().line,
-            })
+        // Optional: 'as' Alias — runner handles alias; parser skips if present
+        if let TokenType::IDENTIFIER(w) = &self.current_token().token_type {
+            if w == "as" {
+                self.advance();
+                // consume alias identifier (single segment)
+                if let TokenType::IDENTIFIER(_alias) = &self.current_token().token_type {
+                    self.advance();
+                } else {
+                    return Err(ParseError::UnexpectedToken {
+                        found: self.current_token().token_type.clone(),
+                        expected: "alias name".to_string(),
+                        line: self.current_token().line,
+                    });
+                }
+            }
         }
+
+        Ok(ASTNode::UsingStatement { namespace_name: namespace, span: Span::unknown() })
     }
 
     /// Parse from statement: from Parent.method(args)
@@ -92,4 +127,4 @@ impl NyashParser {
         // Example: from Animal.constructor() (return value unused)
         Ok(from_call_expr)
     }
-}
+}