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/app/state/runtime.rs

@@ -74,6 +74,13 @@ pub enum TurnEvent {
         kind: String,
         message: String,
     },
+    StreamStart,
+    StreamToken(String),
+    StreamDone(crate::dto::chat::message::ChatMessage),
+    Usage {
+        tokens_in: u64,
+        tokens_out: u64,
+    },
     Error(String),
     Done,
 }