feat: 添加访客登录 API (POST /api/guest-login) 支持网站独立支付

- 新增 web_guest_login handler: 创建访客用户（免微信 code），返回 JWT
- 路由注册在公共区（无需 JWT 认证）
- /payment 页面新增「访客登录」按钮，直接选择套餐支付
- 保留微信小程序登录作为备选
- 已部署到 dev.xmclassmate.top 验证通过

src/handlers/auth.rs

@@ -4,6 +4,7 @@ use serde::{Deserialize, Serialize};
 use reqwest::Client;
 use sqlx::postgres::PgPool;
 use tracing::{debug, error, info, warn};
+use uuid::Uuid;
 
 use crate::auth::{generate_token, generate_refresh_token};
 use crate::db;
@@ -253,6 +254,99 @@ pub struct MockLoginResponse {
     pub user_id: i32,
 }
 
+// ===== 访客登录（免微信，直接网站支付用） =====
+
+#[derive(Debug, Serialize)]
+pub struct GuestLoginResponse {
+    pub success: bool,
+    pub token: String,
+    pub refresh_token: String,
+    pub user_id: i32,
+    pub is_active_member: bool,
+    pub membership_expires_at: Option<String>,
+}
+
+/// POST /api/guest-login
+/// 网站独立支付用：无需微信 code，直接创建访客用户并返回 JWT
+#[post("/api/guest-login")]
+pub async fn web_guest_login(
+    pool: web::Data<PgPool>,
+    app_state: web::Data<AppState>,
+) -> impl Responder {
+    let guest_openid = format!("web_guest_{}", Uuid::new_v4());
+    let guest_name = format!("访客_{}", &guest_openid[10..18]);
+
+    // 创建访客用户
+    let user_id = match sqlx::query_as::<_, (i32,)>(
+        r#"INSERT INTO users (openid, name, type) VALUES ($1, $2, 2)
+           ON CONFLICT (openid) DO UPDATE SET id = users.id RETURNING id"#,
+    )
+    .bind(&guest_openid)
+    .bind(&guest_name)
+    .fetch_one(pool.get_ref())
+    .await
+    {
+        Ok((id,)) => id,
+        Err(e) => {
+            error!("创建访客用户失败: {}", e);
+            return HttpResponse::InternalServerError()
+                .json(ErrorResponse::<()>::error("创建用户失败"));
+        }
+    };
+
+    // 生成 JWT
+    let token = match generate_token(user_id, &guest_openid, 2, &app_state.jwt_secret) {
+        Ok(t) => t,
+        Err(e) => {
+            error!("JWT 生成失败: {}", e);
+            return HttpResponse::InternalServerError()
+                .json(ErrorResponse::<()>::error("生成令牌失败"));
+        }
+    };
+
+    // 生成 refresh_token
+    let refresh_token_str = match generate_refresh_token(user_id, &app_state.jwt_secret) {
+        Ok(t) => t,
+        Err(e) => {
+            error!("refresh_token 生成失败: {}", e);
+            return HttpResponse::InternalServerError()
+                .json(ErrorResponse::<()>::error("生成刷新令牌失败"));
+        }
+    };
+    let refresh_expires_at = Utc::now() + Duration::days(7);
+    if let Err(e) =
+        db::create_refresh_token(pool.get_ref(), user_id, &refresh_token_str, refresh_expires_at).await
+    {
+        warn!("保存 refresh_token 失败（继续）: {}", e);
+    }
+
+    // 查询付费状态
+    let (is_active_member, membership_expires_at): (bool, Option<String>) =
+        match sqlx::query_as::<_, (bool, Option<chrono::DateTime<chrono::Utc>>)>(
+            "SELECT is_member, membership_expires_at FROM users WHERE id = $1",
+        )
+        .bind(user_id)
+        .fetch_optional(pool.get_ref())
+        .await
+        {
+            Ok(Some((is_member, expires))) => {
+                let active = is_member && expires.is_none_or(|e| e > Utc::now());
+                (active, expires.map(|e| e.to_rfc3339()))
+            }
+            _ => (false, None),
+        };
+
+    info!("[GUEST LOGIN] user_id={} 访客登录成功", user_id);
+    HttpResponse::Ok().json(GuestLoginResponse {
+        success: true,
+        token,
+        refresh_token: refresh_token_str,
+        user_id,
+        is_active_member,
+        membership_expires_at,
+    })
+}
+
 /// GET /api/mock-login
 /// 沙箱测试用：无需微信 code，直接返回 JWT
 /// 通过环境变量 MOCK_LOGIN_ENABLED + MOCK_LOGIN_KEY 控制启用