chore: Phase 25.1 完了 - LoopForm v2/Stage1 CLI/環境変数削減 + Phase 26-D からの変更

Phase 25.1 完了成果:
- ✅ LoopForm v2 テスト・ドキュメント・コメント完備
  - 4ケース（A/B/C/D）完全テストカバレッジ
  - 最小再現ケース作成（SSAバグ調査用）
  - SSOT文書作成（loopform_ssot.md）
  - 全ソースに [LoopForm] コメントタグ追加

- ✅ Stage-1 CLI デバッグ環境構築
  - stage1_cli.hako 実装
  - stage1_bridge.rs ブリッジ実装
  - デバッグツール作成（stage1_debug.sh/stage1_minimal.sh）
  - アーキテクチャ改善提案文書

- ✅ 環境変数削減計画策定
  - 25変数の完全調査・分類
  - 6段階削減ロードマップ（25→5、80%削減）
  - 即時削除可能変数特定（NYASH_CONFIG/NYASH_DEBUG）

Phase 26-D からの累積変更:
- PHI実装改善（ExitPhiBuilder/HeaderPhiBuilder等）
- MIRビルダーリファクタリング
- 型伝播・最適化パス改善
- その他約300ファイルの累積変更

🎯 技術的成果:
- SSAバグ根本原因特定（条件分岐内loop変数変更）
- Region+next_iパターン適用完了（UsingCollectorBox等）
- LoopFormパターン文書化・テスト化完了
- セルフホスティング基盤強化

Co-Authored-By: Claude <noreply@anthropic.com>
Co-Authored-By: ChatGPT <noreply@openai.com>
Co-Authored-By: Task Assistant <task@anthropic.com>

src/mir/mod.rs

@@ -9,58 +9,56 @@
 pub mod aot_plan_import;
 pub mod basic_block;
 pub mod builder;
-pub mod definitions;  // Unified MIR definitions (MirCall, Callee, etc.)
+pub mod definitions; // Unified MIR definitions (MirCall, Callee, etc.)
 pub mod effect;
 pub mod function;
 pub mod instruction;
-pub mod instruction_kinds; // small kind-specific metadata (Const/BinOp)
 pub mod instruction_introspection; // Introspection helpers for tests (instruction names)
-pub mod types; // core MIR enums (ConstValue, Ops, MirType)
+pub mod instruction_kinds; // small kind-specific metadata (Const/BinOp)
 pub mod loop_api; // Minimal LoopBuilder facade (adapter-ready)
 pub mod loop_builder; // SSA loop construction with phi nodes
-pub mod ssot; // Shared helpers (SSOT) for instruction lowering
 pub mod optimizer;
+pub mod ssot; // Shared helpers (SSOT) for instruction lowering
+pub mod types; // core MIR enums (ConstValue, Ops, MirType)
 pub mod utils; // Phase 15 control flow utilities for root treatment
-// pub mod lowerers; // reserved: Stage-3 loop lowering (while/for-range)
-pub mod phi_core; // Phase 1 scaffold: unified PHI entry (re-exports only)
-pub mod region; // Phase 25.1l: Region/GC観測レイヤ（LoopForm v2 × RefKind）
+               // pub mod lowerers; // reserved: Stage-3 loop lowering (while/for-range)
+pub mod control_form;
+pub mod function_emission; // FunctionEmissionBox（MirFunction直編集の発行ヘルパ）
+pub mod hints; // scaffold: zero-cost guidance (no-op)
 pub mod optimizer_passes; // optimizer passes (normalize/diagnostics)
 pub mod optimizer_stats; // extracted stats struct
 pub mod passes;
+pub mod phi_core; // Phase 1 scaffold: unified PHI entry (re-exports only)
 pub mod printer;
-pub mod function_emission; // FunctionEmissionBox（MirFunction直編集の発行ヘルパ）
 mod printer_helpers; // internal helpers extracted from printer.rs
-pub mod hints; // scaffold: zero-cost guidance (no-op)
+pub mod region; // Phase 25.1l: Region/GC観測レイヤ（LoopForm v2 × RefKind）
 pub mod slot_registry; // Phase 9.79b.1: method slot resolution (IDs)
 pub mod value_id;
 pub mod value_kind; // Phase 26-A: ValueId型安全化
 pub mod verification;
-pub mod verification_types; // extracted error types // Optimization subpasses (e.g., type_hints)
-pub mod control_form; // Phase 25.1f: Loop/If 共通ビュー（ControlForm）
+pub mod verification_types; // extracted error types // Optimization subpasses (e.g., type_hints) // Phase 25.1f: Loop/If 共通ビュー（ControlForm）
 
 // Re-export main types for easy access
 pub use basic_block::{BasicBlock, BasicBlockId, BasicBlockIdGenerator};
 pub use builder::MirBuilder;
-pub use definitions::{Callee, CallFlags, MirCall};  // Unified call definitions
+pub use definitions::{CallFlags, Callee, MirCall}; // Unified call definitions
 pub use effect::{Effect, EffectMask};
 pub use function::{FunctionSignature, MirFunction, MirModule};
 pub use instruction::MirInstruction;
-pub use types::{
-    BarrierOp, BinaryOp, CompareOp, ConstValue, MirType, TypeOpKind, UnaryOp, WeakRefOp,
-};
 pub use optimizer::MirOptimizer;
 pub use printer::MirPrinter;
 pub use slot_registry::{BoxTypeId, MethodSlot};
+pub use types::{
+    BarrierOp, BinaryOp, CompareOp, ConstValue, MirType, TypeOpKind, UnaryOp, WeakRefOp,
+};
 pub use value_id::{LocalId, ValueId, ValueIdGenerator};
 pub use value_kind::{MirValueKind, TypedValueId}; // Phase 26-A: ValueId型安全化
 pub use verification::MirVerifier;
 pub use verification_types::VerificationError;
 // Phase 15 control flow utilities (段階的根治戦略)
 pub use utils::{
-    is_current_block_terminated,
-    capture_actual_predecessor_and_jump,
-    collect_phi_incoming_if_reachable,
-    execute_statement_with_termination_check,
+    capture_actual_predecessor_and_jump, collect_phi_incoming_if_reachable,
+    execute_statement_with_termination_check, is_current_block_terminated,
 };
 
 /// MIR compilation result