fix(api): 修复验证码repository datetime时区问题 - 数据库naive转aware

SQLAlchemy 从数据库读出的 DateTime 是 naive（不带时区），
但领域模型 VerificationCode 用的是 aware datetime（带 timezone.utc），
直接比较会报 "can't compare offset-naive and offset-aware datetimes"。

修复：_to_entity 时给所有 datetime 字段补 timezone.utc。

影响：send-verification-code 限流检查、bind-contact 验证码校验（is_expired）

packages/adapters/sqlalchemy_impl/verification_code_repository.py

@@ -67,13 +67,24 @@ class SQLAlchemyVerificationCodeRepository(VerificationCodeRepository):
     def _to_entity(model: VerificationCodeModel | None) -> VerificationCode | None:
         if model is None:
             return None
+
+        # SQLAlchemy 从数据库读出的 DateTime 是 naive（不带时区），
+        # 领域模型期望 aware datetime（带 timezone.utc），直接用会报
+        # "can't compare offset-naive and offset-aware datetimes"
+        def _ensure_aware(dt: datetime | None) -> datetime | None:
+            if dt is None:
+                return None
+            if dt.tzinfo is None:
+                return dt.replace(tzinfo=timezone.utc)
+            return dt
+
         return VerificationCode(
             id=model.id,
             recipient=model.recipient,
             code=model.code,
             code_type=model.code_type,
-            expires_at=model.expires_at,
-            used_at=model.used_at,
+            expires_at=_ensure_aware(model.expires_at),
+            used_at=_ensure_aware(model.used_at),
             attempts=model.attempts,
-            created_at=model.created_at,
+            created_at=_ensure_aware(model.created_at),
         )