fix: resolve all clippy warnings and convert integration_tests to custom cfg

- Add type aliases (FileRow, FolderRow, FolderRowPaginated, FolderRowOptUser) to reduce type complexity
- Simplify redundant closures in app_password_handler and webdav_handler
- Remove needless borrow in auth_handler
- Collapse nested if/let chains in login_lockout, webdav_lock, auth, rate_limit
- Box LockEntry in acquire() Err variant to fix large enum variant warning
- Rename DeviceCodeStatus::from_str to parse to avoid should_implement_trait lint
- Add #[allow(clippy::too_many_arguments)] and #[allow(clippy::result_unit_err)] where appropriate
- Convert integration_tests from cargo feature to custom cfg attribute
- Add check-cfg lint config in Cargo.toml for integration_tests cfg

src/application/services/admin_settings_service.rs

@@ -7,8 +7,8 @@ use crate::application::services::auth_application_service::AuthApplicationServi
 use crate::common::config::OidcConfig;
 use crate::common::errors::{DomainError, ErrorKind};
 use crate::domain::repositories::settings_repository::SettingsRepository;
-use crate::infrastructure::services::oidc_service::OidcService;
 use crate::infrastructure::repositories::pg::SettingsPgRepository;
+use crate::infrastructure::services::oidc_service::OidcService;
 
 /// Admin settings service — manages platform configuration in the database.
 ///