Refactor view modules for improved readability and consistency

- Updated markdown rendering logic to use more concise methods for obtaining vector lengths.
- Changed review status display to use the correct flag from settings.
- Cleaned up sidebar rendering code for better formatting and readability.
- Enhanced status bar rendering with improved string formatting and consistent style application.
- Refined workflow panel rendering, ensuring consistent style usage and improved readability.
- Added architecture overview and detailed documentation for backend, data, dependencies, and frontend structures.

src/model/session.rs

@@ -1,9 +1,8 @@
 //! Session metadata: id, title, workspace roots, and message/token counts,
 //! persisted as `session.json` per session directory.
-
-use std::path::{Path, PathBuf};
-use serde::{Deserialize, Serialize};
 use chrono::Utc;
+use serde::{Deserialize, Serialize};
+use std::path::{Path, PathBuf};
 
 /// Metadata for one conversation session (distinct from the message
 /// history itself, which lives in `Conversation`/the msglog).
@@ -108,7 +107,9 @@ impl Session {
     /// contains no valid sessions.
     pub fn list(base_dir: &Path) -> Vec<Self> {
         let sessions_dir = base_dir.join("sessions");
-        let Ok(entries) = std::fs::read_dir(&sessions_dir) else { return Vec::new() };
+        let Ok(entries) = std::fs::read_dir(&sessions_dir) else {
+            return Vec::new();
+        };
         entries
             .filter_map(std::result::Result::ok)
             .filter(|e| e.path().is_dir())