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/controller/command.rs

@@ -13,6 +13,11 @@ pub enum Command {
     Mode(ModeKind),
     Clear,
     Login { provider: String },
+    Edit(String),
+    McpAdd {
+        name: String,
+        command: String,
+    },
     Unknown(String),
 }
 
@@ -50,6 +55,23 @@ pub fn parse_command(text: &str) -> Command {
         "/lesson" => Command::LessonList,
         "/login" if !arg1.is_empty() => Command::Login { provider: arg1.to_string() },
         "/login" => Command::Login { provider: "zen".to_string() },
+        "/edit" if !arg1.is_empty() => Command::Edit(arg1.to_string()),
+        "/edit" => Command::Edit(".".to_string()),
+        "/mcp" if arg1 == "add" && !arg2.is_empty() => {
+            // /mcp add <name> <command> [args...]
+            // name is the first word of arg2, the rest is the command
+            let rest = arg2.trim();
+            if let Some(space) = rest.find(' ') {
+                let name = rest[..space].to_string();
+                let command = rest[space + 1..].trim().to_string();
+                Command::McpAdd { name, command }
+            } else {
+                Command::McpAdd {
+                    name: rest.to_string(),
+                    command: String::new(),
+                }
+            }
+        }
         _ => Command::Unknown(cmd.to_string()),
     }
 }