feat: add editing and MCP command handling, enhance SSE streaming with usage tracking

- Implemented `Edit` and `McpAdd` commands in the command parser and handler.
- Added a new `stream` module to the runtime for handling streaming events.
- Enhanced `SseParser` to parse usage information from SSE events.
- Introduced `ToolCallAccumulator` for tracking tool calls independently.
- Updated `AppStateRest` to include `app_config` and `MiscState` to track `effort_level` and `selected_index`.
- Modified `LlmClient` to support streaming responses with usage tracking.
- Improved error handling and retry logic in the streaming API calls.
- Added tests for new features and improved markdown rendering in the chat view.

src/view/chat.rs

@@ -74,10 +74,9 @@ pub fn draw_chat(frame: &mut Frame, area: Rect, state: &crate::app::state::rest:
         } else {
             msg.content.clone()
         };
-        let content_line = Line::from(vec![
-            Span::styled(format!("{} ", prefix), Style::default().fg(role_color)),
-            Span::styled(content_str, Style::default().fg(Theme::TEXT)),
-        ]);
+        let mut content_spans = vec![Span::styled(format!("{} ", prefix), Style::default().fg(role_color))];
+        content_spans.extend(super::markdown::render_markdown(&content_str, area.width));
+        let content_line = Line::from(content_spans);
 
         display_lines.push(header);
         display_lines.push(content_line);