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/scope_manager.rs

@@ -274,7 +274,10 @@ impl<'a> ScopeManager for Pattern2ScopeManager<'a> {
             if let Some(value_id) = self.condition_env.resolve_var_with_binding(Some(bid), name) {
                 debug.log(
                     "direct",
-                    &format!("BindingId({}) -> ValueId({}) for '{}'", bid.0, value_id.0, name),
+                    &format!(
+                        "BindingId({}) -> ValueId({}) for '{}'",
+                        bid.0, value_id.0, name
+                    ),
                 );
                 return Some(value_id);
             }
@@ -282,7 +285,10 @@ impl<'a> ScopeManager for Pattern2ScopeManager<'a> {
             // Step 2: **NEW (Phase 76)**: Check promoted_bindings map
             if let Some(promoted_bid) = self.carrier_info.resolve_promoted_with_binding(bid) {
                 // Promoted BindingId found, lookup in ConditionEnv
-                if let Some(value_id) = self.condition_env.resolve_var_with_binding(Some(promoted_bid), name) {
+                if let Some(value_id) = self
+                    .condition_env
+                    .resolve_var_with_binding(Some(promoted_bid), name)
+                {
                     debug.log(
                         "promoted",
                         &format!(
@@ -304,7 +310,10 @@ impl<'a> ScopeManager for Pattern2ScopeManager<'a> {
             #[cfg(not(feature = "normalized_dev"))]
             debug.log(
                 "fallback",
-                &format!("BindingId({}) miss, falling back to name '{}' lookup", bid.0, name),
+                &format!(
+                    "BindingId({}) miss, falling back to name '{}' lookup",
+                    bid.0, name
+                ),
             );
         }
 
@@ -331,7 +340,7 @@ mod tests {
             carriers: vec![],
             trim_helper: None,
             promoted_loopbodylocals: vec![],
-#[cfg(feature = "normalized_dev")]
+            #[cfg(feature = "normalized_dev")]
             promoted_bindings: std::collections::BTreeMap::new(),
         };
 
@@ -429,7 +438,7 @@ mod tests {
             carriers: vec![],
             trim_helper: None,
             promoted_loopbodylocals: vec![],
-#[cfg(feature = "normalized_dev")]
+            #[cfg(feature = "normalized_dev")]
             promoted_bindings: std::collections::BTreeMap::new(),
         };
 
@@ -464,7 +473,7 @@ mod tests {
             carriers: vec![],
             trim_helper: None,
             promoted_loopbodylocals: vec![],
-#[cfg(feature = "normalized_dev")]
+            #[cfg(feature = "normalized_dev")]
             promoted_bindings: std::collections::BTreeMap::new(),
         };