feat(workflow): 中断系统（x 杀单 agent / K 杀整个 workflow，Dialog 二次确认）

- claudeCodeBackend 桥接 ctx.signal → runAgent.override.abortController（修 'x' 无效根因：abort 到不了内部 fetch）
- AbortError 识别为 throw WorkflowAbortedError（不再吞成 dead，workflow 能感知被 kill）
- ports.taskRegistrar 加 registerAgentAbort/unregisterAgentAbort/killAgent；service.killAgent(runId, agentId) 精确中断
- 面板键位：'x' 杀当前 agent（agents 列聚焦时） / 'K' 杀整个 workflow；Dialog 二次确认 + confirm 模式吞导航键防误触
- 新增测试 8 项（backend signal bridge / hooks inject / ports killAgent / service killAgent）

Co-Authored-By: glm-5.2 <zai-org@claude-code-best.win>

src/workflow/__tests__/useWorkflowKeyboard.test.ts

@@ -11,12 +11,27 @@ test('q / Esc → quit', () => {
   expect(routeWorkflowKey('', { escape: true })).toBe('quit')
 })
 
-test('x → kill；r → resume；n → newRun', () => {
-  expect(routeWorkflowKey('x', {})).toBe('kill')
+test('x → killAgent；K → killWorkflow；r → resume；n → newRun', () => {
+  expect(routeWorkflowKey('x', {})).toBe('killAgent')
+  expect(routeWorkflowKey('K', {})).toBe('killWorkflow')
   expect(routeWorkflowKey('r', {})).toBe('resume')
   expect(routeWorkflowKey('n', {})).toBe('newRun')
 })
 
+test('confirm 模式：y/Enter → confirmYes；n/Esc/q → confirmNo；其他键 → null', () => {
+  expect(routeWorkflowKey('y', {}, 'confirm')).toBe('confirmYes')
+  expect(routeWorkflowKey('Y', {}, 'confirm')).toBe('confirmYes')
+  expect(routeWorkflowKey('', { return: true }, 'confirm')).toBe('confirmYes')
+  expect(routeWorkflowKey('n', {}, 'confirm')).toBe('confirmNo')
+  expect(routeWorkflowKey('N', {}, 'confirm')).toBe('confirmNo')
+  expect(routeWorkflowKey('', { escape: true }, 'confirm')).toBe('confirmNo')
+  expect(routeWorkflowKey('q', {}, 'confirm')).toBe('confirmNo')
+  // confirm 模式吞掉导航/编辑键，防误触
+  expect(routeWorkflowKey('x', {}, 'confirm')).toBeNull()
+  expect(routeWorkflowKey('', { tab: true }, 'confirm')).toBeNull()
+  expect(routeWorkflowKey('', { upArrow: true }, 'confirm')).toBeNull()
+})
+
 test('←/→ 切焦点列；↑/↓ 列内移动', () => {
   expect(routeWorkflowKey('', { leftArrow: true })).toBe('focusLeft')
   expect(routeWorkflowKey('', { rightArrow: true })).toBe('focusRight')