fix(mir): PHI検証panic修正 - update_cfg()を検証前に呼び出し

A案実装: debug_verify_phi_inputs呼び出し前にCFG predecessorを更新

修正箇所（7箇所）:
- src/mir/builder/phi.rs:50, 73, 132, 143
- src/mir/builder/ops.rs:273, 328, 351

根本原因:
- Branch/Jump命令でsuccessorは即座に更新
- predecessorはupdate_cfg()で遅延再構築
- PHI検証が先に実行されてpredecessor未更新でpanic

解決策:
- 各debug_verify_phi_inputs呼び出し前に
  if let Some(func) = self.current_function.as_mut() {
      func.update_cfg();
  }
  を挿入してCFGを同期

影響: if/else文、論理演算子(&&/||)のPHI生成が正常動作

src/mir/builder/ops.rs

@@ -269,6 +269,9 @@ impl super::MirBuilder {
             self.start_new_block(rhs_join)?;
             let rhs_bool = self.value_gen.next();
             let inputs = vec![(rhs_true_exit, t_id), (rhs_false_exit, f_id)];
+            if let Some(func) = self.current_function.as_mut() {
+                func.update_cfg();
+            }
             if let (Some(func), Some(cur_bb)) = (&self.current_function, self.current_block) {
                 crate::mir::phi_core::common::debug_verify_phi_inputs(func, cur_bb, &inputs);
             }
@@ -324,6 +327,9 @@ impl super::MirBuilder {
             self.start_new_block(rhs_join)?;
             let rhs_bool = self.value_gen.next();
             let inputs = vec![(rhs_true_exit, t_id), (rhs_false_exit, f_id)];
+            if let Some(func) = self.current_function.as_mut() {
+                func.update_cfg();
+            }
             if let (Some(func), Some(cur_bb)) = (&self.current_function, self.current_block) {
                 crate::mir::phi_core::common::debug_verify_phi_inputs(func, cur_bb, &inputs);
             }
@@ -347,6 +353,9 @@ impl super::MirBuilder {
         // Result PHI (bool)
         let result_val = self.value_gen.next();
         let inputs = vec![(then_exit_block, then_value_raw), (else_exit_block, else_value_raw)];
+        if let Some(func) = self.current_function.as_mut() {
+            func.update_cfg();
+        }
         if let (Some(func), Some(cur_bb)) = (&self.current_function, self.current_block) {
             crate::mir::phi_core::common::debug_verify_phi_inputs(func, cur_bb, &inputs);
         }