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

lang/src/vm/hakorune-vm/boxcall_handler.hako

@@ -50,7 +50,7 @@ static box BoxCallHandlerBox {
 
 
     // Guard arguments (no nulls)
-    local _g = ArgsGuardBox.ensure_no_nulls(args_array, method_name + "/" + args_array.size())
+    local _g = ArgsGuardBox.ensure_no_nulls(args_array, method_name + "/" + args_array.length())
     if _g.is_Err() { return _g }
 
     // Extract destination register
@@ -63,7 +63,7 @@ static box BoxCallHandlerBox {
     }
 
     // Prepare method signature for dispatch
-    local arg_count = args_array.size()
+    local arg_count = args_array.length()
     local method_sig = method_name + "/" + arg_count
 
     // Known methods dispatch table
@@ -75,9 +75,9 @@ static box BoxCallHandlerBox {
     } else if method_sig == "lower/0" {
       result_val = receiver.to_lower()
     } else if method_sig == "size/0" {
-      result_val = receiver.size()
+      result_val = receiver.length()
     } else if method_sig == "length/0" {
-      result_val = receiver.size()
+      result_val = receiver.length()
     } else if method_sig == "isEmpty/0" {
       result_val = receiver.isEmpty()
     } else if method_sig == "substring/2" {
@@ -96,9 +96,9 @@ static box BoxCallHandlerBox {
     } else if method_sig == "set/2" {
       result_val = receiver.set(args_array.get(0), args_array.get(1))
     } else if method_sig == "length/0" {
-      result_val = receiver.size()
+      result_val = receiver.length()
     } else if method_sig == "size/0" {
-      result_val = receiver.size()
+      result_val = receiver.length()
     } else if method_sig == "isEmpty/0" {
       result_val = receiver.isEmpty()
     }
@@ -111,7 +111,7 @@ static box BoxCallHandlerBox {
     } else if method_sig == "has/1" {
       result_val = receiver.has(args_array.get(0))
     } else if method_sig == "size/0" {
-      result_val = receiver.size()
+      result_val = receiver.length()
     } else if method_sig == "isEmpty/0" {
       result_val = receiver.isEmpty()
     } else if method_sig == "delete/1" {
@@ -171,7 +171,7 @@ static box BoxCallHandlerBox {
       // No args field, return empty array
       return new ArrayBox()
     }
-    args_start = args_start + args_key.size()
+    args_start = args_start + args_key.length()
 
     // Find array end
     local args_end = StringOps.index_of_from(inst_json, "]", args_start)