Implement chat and markdown views, enhance status bar, and add workflow panel

- Added `chat.rs` for rendering chat messages with timestamps and roles.
- Introduced `markdown.rs` for rendering markdown content with styling.
- Created `status.rs` to display the application status bar with session and message counts.
- Developed `workflow.rs` to show the current workflow status, including tool calls and active jobs.
- Established a `theme.rs` for centralized color management across the UI.
- Updated `mod.rs` to include new modules and manage rendering logic.

src/view/theme.rs

@@ -0,0 +1,26 @@
+use ratatui::style::Color;
+
+pub struct Theme;
+
+impl Theme {
+    pub const PRIMARY: Color = Color::Cyan;
+    pub const SECONDARY: Color = Color::Magenta;
+    pub const SUCCESS: Color = Color::Green;
+    pub const WARNING: Color = Color::Yellow;
+    pub const ERROR: Color = Color::Red;
+    pub const INFO: Color = Color::Blue;
+    pub const TEXT: Color = Color::White;
+    pub const DIM: Color = Color::DarkGray;
+    pub const HIGHLIGHT: Color = Color::LightYellow;
+    pub const BORDER: Color = Color::Gray;
+    pub const ROLE_USER: Color = Color::Green;
+    pub const ROLE_ASSISTANT: Color = Color::Cyan;
+    pub const ROLE_SYSTEM: Color = Color::Blue;
+    pub const ROLE_TOOL: Color = Color::Yellow;
+    pub const BG: Color = Color::Reset;
+    pub const STATUS_BAR_BG: Color = Color::Blue;
+    pub const MODE_AUTO: Color = Color::Green;
+    pub const MODE_NORMAL: Color = Color::Yellow;
+    pub const MODE_PLAN: Color = Color::Cyan;
+    pub const MODE_YOLO: Color = Color::Red;
+}