domain crate code quality cleanup

strip all comments, extract tests to tests/ dirs,
remove #[allow(clippy::...)], extract magic numbers to
constants, refactor schedule engine private methods to
use param structs, add Default impls, clippy.toml for
persistence constructors

crates/domain/src/ports/auth.rs

@@ -1,19 +1,8 @@
-//! Authentication port.
-//!
-//! Abstracts password hashing and verification so the domain layer
-//! never depends on a specific hashing algorithm (bcrypt, argon2, etc.).
-
 use crate::errors::DomainResult;
 
-/// Port for password hashing and verification.
-///
-/// Implementations live in the infra layer (e.g. `BcryptAuthService`).
-/// These methods are intentionally synchronous — hashing libraries are CPU-bound
-/// and should be spawned on a blocking thread pool by the caller if needed.
+// Intentionally sync: CPU-bound hashing should run on a blocking thread pool
 pub trait AuthService: Send + Sync {
-    /// Hash a plaintext password and return the encoded hash string.
     fn hash_password(&self, password: &str) -> DomainResult<String>;
 
-    /// Verify a plaintext password against an encoded hash.
     fn verify_password(&self, password: &str, hash: &str) -> DomainResult<bool>;
 }