fix: resolve clippy warnings and rustfmt issues for CI compliance

Fix all clippy lints (collapsible if, clone on Copy, needless borrow,
redundant bindings, unused params) and apply rustfmt across the codebase.
Update test mocks to match Uuid-based trait signatures.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/application/services/auth_application_service.rs

@@ -17,11 +17,11 @@ use crate::infrastructure::services::jwt_service::JwtTokenService;
 use crate::infrastructure::services::oidc_service::OidcService;
 use crate::infrastructure::services::password_hasher::Argon2PasswordHasher;
 use moka::sync::Cache;
-use uuid::Uuid;
 use std::path::PathBuf;
 use std::sync::Arc;
 use std::sync::RwLock;
 use std::time::Duration;
+use uuid::Uuid;
 
 /// Result of a successful OIDC callback. The handler layer inspects this to
 /// decide whether to redirect to the regular frontend or complete a Nextcloud