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/agent_def/builtin.rs

@@ -1,5 +1,4 @@
 //! Hardcoded built-in subagent definitions (coder, reviewer, researcher, planner).
-
 use crate::app::subagent::spawn::AgentDefinition;
 
 /// Build the fixed list of built-in agent definitions shipped with zesdex.