feat: 添加站点设置中的 favicon URL 支持，更新相关接口和页面

backend/migration/src/lib.rs

@@ -47,6 +47,7 @@ mod m20260402_000036_create_worker_jobs;
 mod m20260402_000037_add_wechat_share_qr_setting_to_site_settings;
 mod m20260402_000038_add_music_enabled_to_site_settings;
 mod m20260402_000039_add_maintenance_mode_to_site_settings;
+mod m20260403_000040_add_favicon_url_to_site_settings;
 pub struct Migrator;
 
 #[async_trait::async_trait]
@@ -98,6 +99,7 @@ impl MigratorTrait for Migrator {
             Box::new(m20260402_000037_add_wechat_share_qr_setting_to_site_settings::Migration),
             Box::new(m20260402_000038_add_music_enabled_to_site_settings::Migration),
             Box::new(m20260402_000039_add_maintenance_mode_to_site_settings::Migration),
+            Box::new(m20260403_000040_add_favicon_url_to_site_settings::Migration),
             // inject-above (do not remove this comment)
         ]
     }