feat: make ArrowCode run as an inline CLI with on-demand full TUI toggle and auto-collapse panels during run

- Establish the inline readline interactive CLI as the default entry mode (Claude Code style)
- Collapse other panels and make them disappear by automatically toggling layoutMode to classic when a prompt starts running
- Directly answer general chat queries using single-turn Orchestrator execution without forcing a multi-agent plan
- Translate command shortcuts starting with '.' to '/' commands
- Support attaching local files to chat context using /add or .add
- Highlight and box code block containers inside the classic chat panel
- Display faint command autocompletion suggestions triggered with Tab/Right-Arrow keys
- Implement a custom animated Unicode thinking spinner for tool runs

Author: Chintanpatel24

src/tui/App.tsx

@@ -315,6 +315,7 @@ export function App(props: {
           break;
         case "run_start":
           setRunActive(true);
+          setLayoutMode("classic");
           setFinalText("");
           setSystemLine(`Running: ${e.prompt.slice(0, 80)}`);
           harness.sessionLog.push("user", e.prompt.slice(0, 200));