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-backend/src/bin/migrate.rs

@@ -1,12 +1,43 @@
-//! Database migration: creates/upgrades SQLite schemas for all sessions.
+//! Database migration binary for zesdex-backend.
+//!
+//! Scans all session directories under the store path and initializes or
+//! upgrades the SQLite schema (`messages.sqlite`) for each one. This is
+//! a standalone CLI tool invoked as `cargo run --bin migrate`.
+//!
+//! ## Workflow
+//! 1. Resolve the base store directory via `Store::new()`
+//! 2. Iterate over each subdirectory under `sessions/`
+//! 3. For each session directory, call `migrate_session_msglog()` to
+//!    create/upgrade the `messages.sqlite` schema
+//! 4. Report count of succeeded and failed migrations
+//! 5. Exit with error if any session failed
+//!
+//! ## Schema
+//! - `messages` table — stores conversation message rows
+//! - `archives` table — stores session archive metadata
+//! - `blobs` table — stores binary blob data per session
+//! - Indexes on `session_id`, `created_at`, and `role` columns
+//!
+//! ## Versioning
+//! SQLite `PRAGMA user_version` tracks schema version for incremental upgrades.
+
 use std::path::Path;
 
+use tracing;
+
+/// Entry point: migrate all session databases.
+///
+/// Flow: load store → iterate sessions → migrate each → summarise.
+///
+/// Returns an error if any session migration failed.
 fn main() -> anyhow::Result<()> {
+    tracing::info!("starting database migration");
     let store = zesdex_entities::domain::common::store::Store::new();
 
-    // Find all session directories
+    // Resolve the sessions directory under the store base path
     let sessions_dir = store.base_dir.join("sessions");
     if !sessions_dir.exists() {
+        tracing::info!("no sessions directory found at {:?}", sessions_dir);
         eprintln!("No sessions directory found, nothing to migrate");
         return Ok(());
     }
@@ -14,25 +45,29 @@ fn main() -> anyhow::Result<()> {
     let mut migrated = 0u32;
     let mut failed = 0u32;
 
+    // Iterate over all session subdirectories
     for entry in std::fs::read_dir(&sessions_dir)? {
         let entry = entry?;
         let path = entry.path();
         if !path.is_dir() {
-            continue;
+            continue; // skip non-directory entries
         }
 
         match migrate_session_msglog(&path) {
             Ok(_) => {
                 migrated += 1;
+                tracing::info!("migrated session: {:?}", path.file_name());
                 eprintln!("Migrated session: {:?}", path.file_name());
             }
             Err(e) => {
                 failed += 1;
+                tracing::error!("failed to migrate session {:?}: {e}", path.file_name());
                 eprintln!("Failed to migrate session {:?}: {e}", path.file_name());
             }
         }
     }
 
+    tracing::info!("migration complete: {migrated} succeeded, {failed} failed");
     eprintln!("Migration complete: {migrated} succeeded, {failed} failed");
     if failed > 0 {
         anyhow::bail!("{failed} session(s) failed to migrate");
@@ -40,8 +75,18 @@ fn main() -> anyhow::Result<()> {
     Ok(())
 }
 
-/// Open a session's `messages.sqlite` and initialize its schema.
+/// Open (or create) a session's `messages.sqlite` and ensure its schema is current.
+///
+/// Flow: resolve path → open/ create DB → set PRAGMAs → create tables → upgrade version.
+///
+/// ## Parameters
+/// - `session_dir`: path to the individual session directory
+///
+/// ## Returns
+/// - `Ok(())` on success
+/// - `Err` if file I/O or SQLite operations fail
 fn migrate_session_msglog(session_dir: &Path) -> anyhow::Result<()> {
+    tracing::debug!("migrating session at {:?}", session_dir);
     let msglog_path = session_dir.join("messages.sqlite");
 
     if let Some(parent) = msglog_path.parent() {

crates/zesdex-backend/src/bin/seed.rs

@@ -1,6 +1,28 @@
-//! Database seeder: initializes store directories, creates default settings
-//! and app_config, and populates a default session for development.
+//! Database seeder binary for zesdex-backend.
+//!
+//! Standalone CLI tool invoked as `cargo run --bin seed` to initialise
+//! the store directory structure and create default configuration files
+//! plus a seed session for development and testing.
+//!
+//! ## Workflow
+//! 1. Create the base store directory and all subdirectories
+//! 2. Write default `settings.json` if absent (atomic write via temp file + rename)
+//! 3. Write default `app_config.json` if absent (same atomic pattern)
+//! 4. Create standard subdirectories: `memories`, `scratch`, `session-images`, `downloads`
+//! 5. Create a single seed `Session` with a random UUID
+//!
+//! ## Safety
+//! All file writes use an atomic temp-file + rename pattern to prevent
+//! partial writes from corrupting configuration files during crashes.
 
+use tracing;
+
+/// Entry point: initialise the store and create seed data.
+///
+/// Flow: init store dirs → write default settings → write default config →
+///       create subdirs → create seed session.
+///
+/// This is idempotent: if settings or config already exist they are skipped.
 fn main() -> anyhow::Result<()> {
     let store = zesdex_entities::domain::common::store::Store::new();
     store.ensure_dirs()?;