feat(arena): Add agent collaboration arena feature

Introduces a new Arena system for running multiple AI agents in parallel
terminal sessions with support for iTerm and Tmux backends.

Core:
- Add ArenaManager and ArenaAgentClient for orchestrating multi-agent sessions
- Add terminal backends (ITermBackend, TmuxBackend) with feature detection
- Add git worktree service for isolated agent workspaces
- Add arena event system for real-time status updates

CLI:
- Add /arena command with start, stop, status, and select subcommands
- Add Arena dialogs (Select, Start, Status, Stop)
- Add ArenaCards component for displaying parallel agent outputs
- Consolidate message components into StatusMessages and ConversationMessages
- Add MultiSelect component for agent selection

Config:
- Add arena-related settings to schema and config

Co-authored-by: Qwen-Coder <qwen-coder@alibabacloud.com>

packages/cli/src/ui/contexts/UIStateContext.tsx

@@ -33,6 +33,7 @@ import type { UpdateObject } from '../utils/updateCheck.js';
 import { type UseHistoryManagerReturn } from '../hooks/useHistoryManager.js';
 import { type RestartReason } from '../hooks/useIdeTrustListener.js';
 import { type CodingPlanUpdateRequest } from '../hooks/useCodingPlanUpdates.js';
+import { type ArenaDialogType } from '../hooks/useArenaCommand.js';
 
 export interface UIState {
   history: HistoryItem[];
@@ -52,6 +53,7 @@ export interface UIState {
   quittingMessages: HistoryItem[] | null;
   isSettingsDialogOpen: boolean;
   isModelDialogOpen: boolean;
+  activeArenaDialog: ArenaDialogType;
   isPermissionsDialogOpen: boolean;
   isApprovalModeDialogOpen: boolean;
   isResumeDialogOpen: boolean;