refactor: 移除邮件功能

发信能力整体下线，唯一的调用方（忘记密码）前端也从来没接过。

- utils/shortcuts.py 删 send_email，连带四个 django.core.mail 相关 import
- account/tasks.py 整个删除，里面只有 send_email_async 一个 actor
- 删 ApplyResetPasswordAPI / ResetPasswordAPI 及其路由、serializer，
  User.reset_password_token 和 reset_password_token_expire_time 两个
  字段（account/0010）
- 删 SMTPAPI / SMTPTestAPI 及其路由、三个 SMTP serializer、
  SysOptions.smtp_config
- account/templates/reset_password_email.html

options/0003 数据迁移删掉库里的 smtp_config 行：_init_option 会为每个
OptionKey 建行，key 从代码里去掉后它会变成孤儿，而且配过 SMTP 的话
value 里存着明文密码。

保留 ResetUserPasswordAPI（管理端直接重置密码，不发信，前端在用）和
User.email（注册要填）。

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

conf/serializers.py

@@ -3,22 +3,6 @@ from utils.api import serializers
 from .models import JudgeServer
 
 
-class EditSMTPConfigSerializer(serializers.Serializer):
-    server = serializers.CharField(max_length=128)
-    port = serializers.IntegerField(default=25)
-    email = serializers.CharField(max_length=256)
-    password = serializers.CharField(max_length=128, required=False, allow_null=True, allow_blank=True)
-    tls = serializers.BooleanField()
-
-
-class CreateSMTPConfigSerializer(EditSMTPConfigSerializer):
-    password = serializers.CharField(max_length=128)
-
-
-class TestSMTPConfigSerializer(serializers.Serializer):
-    email = serializers.EmailField()
-
-
 class CreateEditWebsiteConfigSerializer(serializers.Serializer):
     website_base_url = serializers.CharField(max_length=128)
     website_name = serializers.CharField(max_length=64)

conf/urls/admin.py

@@ -1,18 +1,14 @@
 from django.urls import path
 
 from ..views import (
-    SMTPAPI,
     DashboardInfoAPI,
     JudgeServerAPI,
     RandomUsernameAPI,
-    SMTPTestAPI,
     TestCasePruneAPI,
     WebsiteConfigAPI,
 )
 
 urlpatterns = [
-    path("smtp", SMTPAPI.as_view()),  # DEPRECATED: 前端未调用
-    path("smtp_test", SMTPTestAPI.as_view()),  # DEPRECATED: 前端未调用
     path("website", WebsiteConfigAPI.as_view()),
     path("random_user", RandomUsernameAPI.as_view()),
     path("judge_server", JudgeServerAPI.as_view()),

conf/views.py

@@ -4,7 +4,6 @@ import os
 import random
 import re
 import shutil
-import smtplib
 from datetime import timedelta
 
 from asgiref.sync import sync_to_async
@@ -20,83 +19,19 @@ from problem.models import Problem
 from submission.models import Submission
 from utils.api import APIView, AsyncAPIView, CSRFExemptAPIView, validate_serializer
 from utils.cache import JsonDataLoader
-from utils.shortcuts import get_env, send_email
+from utils.shortcuts import get_env
 from utils.websocket import push_config_update
 from utils.xss_filter import XSSHtml
 
 from .models import JudgeServer
 from .serializers import (
     CreateEditWebsiteConfigSerializer,
-    CreateSMTPConfigSerializer,
     EditJudgeServerSerializer,
-    EditSMTPConfigSerializer,
     JudgeServerHeartbeatSerializer,
     JudgeServerSerializer,
-    TestSMTPConfigSerializer,
 )
 
 
-# DEPRECATED: 前端未调用 (2026-05-26)
-class SMTPAPI(APIView):
-    @super_admin_required
-    def get(self, request):
-        smtp = SysOptions.smtp_config
-        if not smtp:
-            return self.success(None)
-        smtp.pop("password")
-        return self.success(smtp)
-
-    @super_admin_required
-    @validate_serializer(CreateSMTPConfigSerializer)
-    def post(self, request):
-        SysOptions.smtp_config = request.data
-        return self.success()
-
-    @super_admin_required
-    @validate_serializer(EditSMTPConfigSerializer)
-    def put(self, request):
-        smtp = SysOptions.smtp_config
-        data = request.data
-        for item in ["server", "port", "email", "tls"]:
-            smtp[item] = data[item]
-        if "password" in data:
-            smtp["password"] = data["password"]
-        SysOptions.smtp_config = smtp
-        return self.success()
-
-
-# DEPRECATED: 前端未调用 (2026-05-26)
-class SMTPTestAPI(APIView):
-    @super_admin_required
-    @validate_serializer(TestSMTPConfigSerializer)
-    def post(self, request):
-        if not SysOptions.smtp_config:
-            return self.error("Please setup SMTP config at first")
-        try:
-            send_email(
-                smtp_config=SysOptions.smtp_config,
-                from_name=SysOptions.website_name_shortcut,
-                to_name=request.user.username,
-                to_email=request.data["email"],
-                subject="You have successfully configured SMTP",
-                content="You have successfully configured SMTP",
-            )
-        except smtplib.SMTPResponseException as e:
-            # guess error message encoding
-            msg = b"Failed to send email"
-            try:
-                msg = e.smtp_error
-                # qq mail
-                msg = msg.decode("gbk")
-            except Exception:
-                msg = msg.decode("utf-8", "ignore")
-            return self.error(msg)
-        except Exception as e:
-            msg = str(e)
-            return self.error(msg)
-        return self.success()
-
-
 class WebsiteConfigAPI(AsyncAPIView):
     async def get(self, request):
         ret = await SysOptions.aget_many(