docs: tambah doc comment, logging, dan inline comments di semua 255 file

Meliputi:
- File-level //! doc comment: tujuan file, alur kerja, komponen utama
- Function-level /// doc comment: apa, parameter, return, flow, edge cases
- Struct/enum/trait /// doc comment: peran, field docs
- Tracing logging (tracing::info!/debug!/trace!/warn!/error!) di setiap fungsi
- Inline comments untuk variable dan branching logic penting
- Seluruh 8 crates di workspace: zesdex-backend, zesdex-cms, zesdex-entities,
  zesdex-iam, zesdex-infra, zesdex-ipc, zesdex-middleware, zesdex-utils
- Build: 0 errors, 242/242 tests passed

crates/zesdex-iam/src/domain/repository.rs

@@ -1,4 +1,14 @@
 //! Repository trait definitions (pure — no impls, no concrete persistence).
+//!
+//! Defines the repository contracts that infrastructure adapters implement.
+//! Following clean architecture, domain code depends only on these traits,
+//! not on concrete persistence libraries.
+//!
+//! # Traits
+//!
+//! - [`SessionRepository`] — CRUD for session metadata
+//! - [`SessionLockRepository`] — acquire/release/liveness for session locks
+//! - [`OAuthRepository`] — persist/load OAuth tokens
 use std::path::Path;
 
 use crate::domain::oauth::OAuthToken;