refactor(mir): Phase 139-P3-B - RoutingDecision を enum 対応 + レガシー削除

- RoutingDecision の missing_caps を Vec<CapabilityTag> に変更（型安全化）
- error_tags は to_tag() メソッドで自動生成
- 全 callsite を enum variant に修正
- capability_tags モジュール（文字列定数群）を完全削除
- 全テスト PASS（型安全性向上を確認）
- フォーマット適用

src/mir/join_ir/lowering/mod.rs

@@ -25,8 +25,6 @@ pub mod carrier_info; // Phase 196: Carrier metadata for loop lowering
 pub(crate) mod carrier_update_emitter; // Phase 179: Carrier update instruction emission
 pub(crate) mod common; // Internal lowering utilities
 pub mod complex_addend_normalizer; // Phase 192: Complex addend normalization (AST preprocessing)
-pub mod debug_output_box; // Phase 85: Centralized debug output management
-pub mod error_tags; // Phase 86: Centralized error message formatting
 pub mod condition_env; // Phase 171-fix: Condition expression environment
 pub(crate) mod condition_lowerer; // Phase 171-fix: Core condition lowering logic
 pub mod condition_lowering_box; // Phase 244: Unified condition lowering interface (trait-based)
@@ -34,7 +32,9 @@ pub mod condition_pattern; // Phase 219-fix: If condition pattern detection (sim
 pub mod condition_to_joinir; // Phase 169: JoinIR condition lowering orchestrator (refactored)
 pub(crate) mod condition_var_extractor; // Phase 171-fix: Variable extraction from condition AST
 pub mod continue_branch_normalizer; // Phase 33-19: Continue branch normalization for Pattern B
+pub mod debug_output_box; // Phase 85: Centralized debug output management
 pub mod digitpos_condition_normalizer; // Phase 224-E: DigitPos condition normalizer (digit_pos < 0 → !is_digit_pos)
+pub mod error_tags; // Phase 86: Centralized error message formatting
 pub(crate) mod exit_args_resolver; // Internal exit argument resolution
 pub mod expr_lowerer; // Phase 231: Unified expression lowering with scope management
 pub mod funcscanner_append_defs;
@@ -64,12 +64,12 @@ pub(crate) mod loop_view_builder; // Phase 33-23: Loop lowering dispatch
 pub mod loop_with_break_minimal; // Phase 188-Impl-2: Pattern 2 minimal lowerer
 pub mod loop_with_continue_minimal;
 pub mod method_call_lowerer; // Phase 224-B: MethodCall lowering (metadata-driven)
-pub(crate) mod step_schedule; // Phase 47-A: Generic step scheduler for P2/P3 (renamed from pattern2_step_schedule)
 pub mod method_return_hint; // Phase 83: P3-D 既知メソッド戻り値型推論箱
 pub mod scope_manager; // Phase 231: Unified variable scope management // Phase 195: Pattern 4 minimal lowerer
 #[cfg(feature = "normalized_dev")]
-pub mod scope_manager_bindingid_poc; // Phase 73: BindingId-based scope PoC (dev-only)
-                       // Phase 242-EX-A: loop_with_if_phi_minimal removed - replaced by loop_with_if_phi_if_sum
+pub mod scope_manager_bindingid_poc;
+pub(crate) mod step_schedule; // Phase 47-A: Generic step scheduler for P2/P3 (renamed from pattern2_step_schedule) // Phase 73: BindingId-based scope PoC (dev-only)
+                                                                                                                    // Phase 242-EX-A: loop_with_if_phi_minimal removed - replaced by loop_with_if_phi_if_sum
 pub mod loop_with_if_phi_if_sum; // Phase 213: Pattern 3 AST-based if-sum lowerer (Phase 242-EX-A: supports complex conditions)
 pub mod min_loop;
 pub mod simple_while_minimal; // Phase 188-Impl-1: Pattern 1 minimal lowerer