feat(core,cli)!: Implement in-process agent backend for arenas

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

Add InProcessBackend to run subagents in-process rather than via subprocess,

enabling faster initialization and better resource management for agent

collaboration arenas.

Key changes:

- Add InProcessBackend with sandboxed in-process agent execution

- Refactor agent runtime into headless vs interactive modes

- Add AsyncMessageQueue utility for agent message passing

- Update ArenaManager with backend selection (in-process vs subprocess)

- Refactor subagent types/exports; consolidate in subagents/types

- Remove deprecated agent-hooks.ts (functionality merged into runtime)

- Update task tool to support new agent lifecycle

Breaking: Subagent type exports restructured; import from subagents/types

packages/cli/src/ui/components/ArenaStatusDialog.tsx

@@ -10,7 +10,7 @@ import { Box, Text } from 'ink';
 import {
   type ArenaManager,
   type ArenaAgentState,
-  ArenaAgentStatus,
+  isTerminalStatus,
   ArenaSessionStatus,
 } from '@qwen-code/qwen-code-core';
 import { theme } from '../semantic-colors.js';
@@ -42,11 +42,7 @@ function pad(
 }
 
 function getElapsedMs(agent: ArenaAgentState): number {
-  if (
-    agent.status === ArenaAgentStatus.COMPLETED ||
-    agent.status === ArenaAgentStatus.TERMINATED ||
-    agent.status === ArenaAgentStatus.CANCELLED
-  ) {
+  if (isTerminalStatus(agent.status)) {
     return agent.stats.durationMs;
   }
   return Date.now() - agent.startedAt;