fix: 修复 desc 保留关键字导致的 SQL 语法错误

desc 是 PostgreSQL 保留关键字，需要加双引号转义

src/db.rs

@@ -249,7 +249,7 @@ pub async fn delete_weather_data(
 pub async fn get_user_by_id(pool: &PgPool, user_id: i32) -> Result<User, String> {
     let query = r#"
         SELECT 
-            id, name, openid, phone, type, desc, is_paid, is_admin, paid_expires_at
+            id, name, openid, phone, type, "desc", is_paid, is_admin, paid_expires_at
         FROM users
         WHERE id = $1
     "#;