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/view/overlays/rewind.rs

@@ -1,15 +1,26 @@
+//! Overlay: Rewind / session history — shows recent messages and lets the user
+//! pick a point to rewind the transcript back to.
+//!
+//! Flow: reads the last 8 messages from `state.transcript_cache.messages`,
+//! renders each with a role tag and content preview; an overflow note is
+//! appended when there are more than 8 messages. The input controller handles
+//! ↑/↓ navigation and Enter to confirm the rewind point.
+
 use ratatui::style::{Modifier, Style};
 use ratatui::text::{Line, Span};
 use ratatui::widgets::{Block, Paragraph};
 use ratatui::Frame;
 use crate::view::theme::Theme;
+use tracing;
 
+/// Render the Rewind overlay — message list with role tags and previews.
 pub fn render(
     frame: &mut Frame,
     area: ratatui::layout::Rect,
     block: Block<'static>,
     state: &crate::app::state::rest::AppStateRest,
 ) {
+    tracing::debug!("overlay: Rewind (messages={})", state.transcript_cache.messages.len());
     let block = block
         .title(Span::styled(
             " Rewind ",