[Feature Request] Allow default expiry time for a model

Currently we are able to set an expiry after saving the model.

class Like(HashModel):
    user_id: str
    liked_user_id: str

    @root_validator()
    def assign_pk(cls, values):
        values["pk"] = f"{values['user_id']}:{values['liked_user_id']}"
        return values

    class Meta:
        database = redis_conn

like1 = Like(user_id="1", liked_user_id="2")
like1.expire(120)

I'd like all my 'Like' instances to have a default expiry time, instead of defining it each time and updating redis in the background.

Start by reading the HashModel and expire behavior used in the Like example, then inspect how model Meta configuration is handled. Define how a model-level default expiry should apply to newly saved instances and add coverage showing that Like instances receive the configured expiry without calling expire each time.