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/dto/chat/message.rs

@@ -1,6 +1,5 @@
 //! Chat message types shared across the DTO layer: `Role` and `ChatMessage`
 //! with convenience constructors.
-
 use serde::{Deserialize, Serialize};
 
 /// The conversation participant who authored a message.
@@ -17,6 +16,21 @@ pub enum Role {
 }
 
 impl Role {
+    /// Return the role as a lowercase string.
+    pub fn as_str(&self) -> &'static str {
+        match self {
+            Role::User => "user",
+            Role::Assistant => "assistant",
+            Role::System => "system",
+            Role::Tool => "tool",
+        }
+    }
+}
+
+impl std::fmt::Display for Role {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.write_str(self.as_str())
+    }
 }
 
 /// A single message in a conversation, compatible with the OpenAI/Anthropic