modify: auth插件拆分，将token签发部分交给网关

workers/auth_oauth/phone_send_code.toml

@@ -0,0 +1,12 @@
+[POST]
+summary = "手机验证码登录：下发验证码"
+docstring = "生成 6 位验证码存共享缓存（300s）。演示模式随响应返回 dev_code，生产接短信通道后返回 dev_code=null。"
+auth_required = false
+cacheable = false
+params = ["phone: str"]
+
+[POST.response_model]
+result = { type = "str", required = true }
+message = { type = "str", required = true }
+expires_in = { type = "int", required = false, default = 300 }
+dev_code = { type = "str", required = false }