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/tests/parser_semicolon.rs

@@ -0,0 +1,26 @@
+use crate::parser::NyashParser;
+
+#[test]
+fn parse_top_level_semicolons_optional() {
+    let src = r#"
+        local a = 1; local b = 2
+        return a + b;
+    "#;
+    let ast = NyashParser::parse_from_string(src).expect("parser should accept semicolons by default");
+    // Smoke: just ensure it parses into a Program
+    match ast { crate::ast::ASTNode::Program { .. } => {}, _ => panic!("expected Program") }
+}
+
+#[test]
+fn parse_block_with_semicolons() {
+    let src = r#"
+        static box Main {
+          static method main() {
+            local out = ""; local digits = "0123456789"; return 0
+          }
+        }
+    "#;
+    let ast = NyashParser::parse_from_string(src).expect("parser should accept semicolons inside blocks");
+    match ast { crate::ast::ASTNode::Program { .. } => {}, _ => panic!("expected Program") }
+}
+