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/interfaces/api/handlers/caldav_handler.rs

@@ -32,10 +32,10 @@ use crate::application::dtos::calendar_dto::{
     CreateCalendarDto, CreateEventICalDto, UpdateCalendarDto,
 };
 use crate::application::ports::calendar_ports::CalendarUseCase;
+use crate::application::services::calendar_service::CalendarService;
 use crate::common::di::AppState;
 use crate::interfaces::errors::AppError;
 use crate::interfaces::middleware::auth::CurrentUser;
-use crate::application::services::calendar_service::CalendarService;
 
 const HEADER_DAV: HeaderName = HeaderName::from_static("dav");