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-cms/src/infrastructure/http/dto.rs

@@ -1,8 +1,20 @@
-//! CMS-specific DTOs (Data Transfer Objects) for the REST API.
+//! Data Transfer Objects (DTOs) for the CMS REST API.
 //!
 //! These types define the wire format accepted and returned by HTTP handlers.
-//! They are independent of the domain entities so the API contract can
-//! evolve without coupling to the domain model.
+//! They are intentionally independent of the domain entities so the API
+//! contract can evolve without coupling to the domain model.
+//!
+//! ## DTOs
+//! - `SettingsUpdateRequest` — partial-update body for PUT /settings
+//! - `SettingsResponse` — response body for GET /settings (API keys redacted)
+//! - `MemoryCreateRequest` — request body for POST /memories
+//! - `MemoryResponse` — response body for memory operations
+//! - `ConversationResponse` — response body for GET /conversation
+//!
+//! ## Conventions
+//! - `From<DomainType>` impls convert domain entities → DTO responses
+//! - API key values are **redacted** in responses (only key names exposed)
+//! - Request fields use `Option` to support partial updates
 
 use serde::{Deserialize, Serialize};
 
@@ -53,6 +65,10 @@ pub struct SettingsResponse {
     pub hive_mind_node_timeout_ms: u64,
 }
 
+/// Convert a domain `Settings` entity into its API response representation.
+///
+/// ## Side-effects
+/// - API key **values are redacted** — only key names are exposed.
 impl From<crate::domain::settings::Settings> for SettingsResponse {
     fn from(s: crate::domain::settings::Settings) -> Self {
         Self {
@@ -112,6 +128,7 @@ pub struct MemoryResponse {
     pub provenances: Vec<String>,
 }
 
+/// Convert a domain `Memory` entity into its API response representation.
 impl From<crate::domain::memory::Memory> for MemoryResponse {
     fn from(m: crate::domain::memory::Memory) -> Self {
         Self {
@@ -146,6 +163,11 @@ pub struct ConversationResponse {
     pub temperature: Option<f32>,
 }
 
+/// Convert a domain `Conversation` entity into its API response summary.
+///
+/// ## Note
+/// Only metadata is included (message count, model, system prompt);
+/// individual messages are not returned in this response.
 impl From<crate::domain::conversation::Conversation> for ConversationResponse {
     fn from(c: crate::domain::conversation::Conversation) -> Self {
         let message_count = c.len();