refactor: replace Task tool with Agent tool and fix schema compliance

## Task -> Agent Replacement
- Replace all Task({}) calls with Agent({}) across .claude/ directory
- Update allowed-tools declarations from Task to Agent
- Update documentation references from "Task tool" to "Agent tool"

## Schema Compliance Fixes

### Agent Schema
- Add missing required `description` parameter in 6 files
- Add missing `run_in_background: false` for subagent calls
- Add missing `subagent_type` parameter

### AskUserQuestion Schema
- Fix issue-manage/SKILL.md: reduce options from 5 to 4 (max allowed)

### SendMessage Schema
- Fix team-worker.md: use correct params (type, content, summary)
- Remove invalid `team_name` parameter

### TaskCreate/TaskUpdate Schema
- Remove invalid `blockedBy`, `owner`, `status` from TaskCreate calls
- Use separate TaskUpdate calls for dependencies and ownership
- Fix TaskUpdate syntax to use object parameter

### TeamDelete Schema
- Remove parameters from TeamDelete() calls (should be no params)

### TaskOutput Schema
- Fix Python-style syntax to JavaScript object syntax

## Files Changed
- 146 files updated across commands/, skills/, skills_lib/, agents/

ccw/frontend/src/components/ChunkErrorBoundary.tsx

@@ -22,6 +22,15 @@ interface ChunkErrorBoundaryState {
  * Error displayed when a chunk fails to load
  */
 function ChunkLoadError({ error, onRetry }: { error: Error | null; onRetry: () => void }) {
+  const handleGoBack = () => {
+    // Try to go back in history, fallback to home if no history
+    if (window.history.length > 1) {
+      window.history.back();
+    } else {
+      window.location.href = '/';
+    }
+  };
+
   return (
     <div className="flex items-center justify-center h-full p-8">
       <div className="text-center max-w-md">
@@ -46,11 +55,14 @@ function ChunkLoadError({ error, onRetry }: { error: Error | null; onRetry: () =
             ? 'A network error occurred while loading this page. Please check your connection and try again.'
             : 'An error occurred while loading this page. Please try refreshing.'}
         </p>
-        <div className="flex gap-3 justify-center">
+        <div className="flex gap-3 justify-center flex-wrap">
           <Button onClick={onRetry} variant="default">
             Try Again
           </Button>
-          <Button onClick={() => window.location.href = '/'} variant="outline">
+          <Button onClick={handleGoBack} variant="outline">
+            Go Back
+          </Button>
+          <Button onClick={() => window.location.href = '/'} variant="ghost">
             Go Home
           </Button>
         </div>

ccw/frontend/src/locales/en/team.json

@@ -47,6 +47,9 @@
     "artifacts": "Artifacts",
     "messages": "Messages"
   },
+  "error": {
+    "loadFailed": "Failed to Load Team Data"
+  },
   "artifacts": {
     "title": "Team Artifacts",
     "plan": "Plan",

ccw/frontend/src/locales/zh/team.json

@@ -47,6 +47,9 @@
     "artifacts": "产物",
     "messages": "消息"
   },
+  "error": {
+    "loadFailed": "加载团队数据失败"
+  },
   "artifacts": {
     "title": "团队产物",
     "plan": "计划",

ccw/frontend/src/pages/TeamPage.tsx

@@ -3,10 +3,11 @@
 // ========================================
 // Main page for team execution - list/detail dual view with tabbed detail
 
-import { useMemo } from 'react';
+import { useMemo, useEffect } from 'react';
 import { useIntl } from 'react-intl';
-import { Package, MessageSquare, Maximize2, Minimize2, GitBranch } from 'lucide-react';
+import { Package, MessageSquare, Maximize2, Minimize2, GitBranch, AlertTriangle } from 'lucide-react';
 import { Card, CardContent } from '@/components/ui/Card';
+import { Button } from '@/components/ui/Button';
 import { cn } from '@/lib/utils';
 import { useAppStore, selectIsImmersiveMode } from '@/stores/appStore';
 import { TabsNavigation, type TabItem } from '@/components/ui/TabsNavigation';
@@ -43,7 +44,7 @@ export function TeamPage() {
   const toggleImmersiveMode = useAppStore((s) => s.toggleImmersiveMode);
 
   // Data hooks
-  const { teams } = useTeams(locationFilter);
+  const { teams, error: teamsError, isLoading: teamsLoading } = useTeams(locationFilter);
   const { messages, total: messageTotal } = useTeamMessages(
     viewMode === 'detail' ? selectedTeam : null,
     messageFilter
@@ -58,6 +59,14 @@ export function TeamPage() {
     [teams, selectedTeam]
   );
 
+  // Auto-reset to list view when in detail mode but team data is missing after loading
+  useEffect(() => {
+    if (viewMode === 'detail' && selectedTeam && !teamsLoading && teams.length > 0 && !teamData) {
+      // Team no longer exists or is filtered out, return to list
+      backToList();
+    }
+  }, [viewMode, selectedTeam, teamsLoading, teams.length, teamData, backToList]);
+
   // Derive dynamic pipeline stages and multi-phase info
   const stages = useMemo(
     () =>
@@ -77,6 +86,36 @@ export function TeamPage() {
     [teamData?.role_state]
   );
 
+  // Error state - show error page with back button when API fails
+  if (teamsError && viewMode === 'detail') {
+    return (
+      <div className="flex items-center justify-center min-h-[400px] p-8">
+        <div className="text-center max-w-md">
+          <div className="mb-4">
+            <AlertTriangle className="w-16 h-16 mx-auto text-destructive" />
+          </div>
+          <h2 className="text-xl font-semibold mb-2">
+            {formatMessage({ id: 'team.error.loadFailed' })}
+          </h2>
+          <p className="text-muted-foreground mb-6">
+            {teamsError instanceof Error ? teamsError.message : String(teamsError)}
+          </p>
+          <div className="flex gap-3 justify-center">
+            <Button onClick={backToList} variant="default">
+              {formatMessage({ id: 'team.detail.backToList' })}
+            </Button>
+            <Button
+              onClick={() => window.location.reload()}
+              variant="outline"
+            >
+              {formatMessage({ id: 'common.actions.retry' })}
+            </Button>
+          </div>
+        </div>
+      </div>
+    );
+  }
+
   // List view (also fallback when selected team data is not available)
   if (viewMode === 'list' || !selectedTeam || (viewMode === 'detail' && teams.length > 0 && !teamData)) {
     return (