feat(queue): implement queue scheduler service and API routes

- Added QueueSchedulerService to manage task queue lifecycle, including state machine, dependency resolution, and session management.
- Implemented HTTP API endpoints for queue scheduling:
  - POST /api/queue/execute: Submit items to the scheduler.
  - GET /api/queue/scheduler/state: Retrieve full scheduler state.
  - POST /api/queue/scheduler/start: Start scheduling loop with items.
  - POST /api/queue/scheduler/pause: Pause scheduling.
  - POST /api/queue/scheduler/stop: Graceful stop of the scheduler.
  - POST /api/queue/scheduler/config: Update scheduler configuration.
- Introduced types for queue items, scheduler state, and WebSocket messages to ensure type safety and compatibility with the backend.
- Added static model lists for LiteLLM as a fallback for available models.

ccw/frontend/src/hooks/useNativeSessions.ts

@@ -0,0 +1,127 @@
+// ========================================
+// useNativeSessions Hook
+// ========================================
+// TanStack Query hook for native CLI sessions list
+
+import React from 'react';
+import { useQuery } from '@tanstack/react-query';
+import {
+  fetchNativeSessions,
+  type NativeSessionListItem,
+  type NativeSessionsListResponse,
+} from '../lib/api';
+import { useWorkflowStore, selectProjectPath } from '@/stores/workflowStore';
+import { workspaceQueryKeys } from '@/lib/queryKeys';
+
+// ========== Constants ==========
+
+const STALE_TIME = 30 * 1000;
+const GC_TIME = 5 * 60 * 1000;
+
+// ========== Types ==========
+
+export type NativeTool = 'gemini' | 'qwen' | 'codex' | 'claude' | 'opencode';
+
+export interface UseNativeSessionsOptions {
+  /** Filter by tool type */
+  tool?: NativeTool;
+  /** Override default stale time (ms) */
+  staleTime?: number;
+  /** Override default gc time (ms) */
+  gcTime?: number;
+  /** Enable/disable the query */
+  enabled?: boolean;
+}
+
+export interface ByToolRecord {
+  [tool: string]: NativeSessionListItem[];
+}
+
+export interface UseNativeSessionsReturn {
+  /** All sessions data */
+  sessions: NativeSessionListItem[];
+  /** Sessions grouped by tool */
+  byTool: ByToolRecord;
+  /** Total count from API */
+  count: number;
+  /** Loading state for initial fetch */
+  isLoading: boolean;
+  /** Fetching state (initial or refetch) */
+  isFetching: boolean;
+  /** Error object if query failed */
+  error: Error | null;
+  /** Manually refetch data */
+  refetch: () => Promise<void>;
+}
+
+// ========== Helper Functions ==========
+
+/**
+ * Group sessions by tool type
+ */
+function groupByTool(sessions: NativeSessionListItem[]): ByToolRecord {
+  return sessions.reduce<ByToolRecord>((acc, session) => {
+    const tool = session.tool;
+    if (!acc[tool]) {
+      acc[tool] = [];
+    }
+    acc[tool].push(session);
+    return acc;
+  }, {});
+}
+
+// ========== Hook ==========
+
+/**
+ * Hook for fetching native CLI sessions list
+ *
+ * @example
+ * ```tsx
+ * const { sessions, byTool, isLoading } = useNativeSessions();
+ * const geminiSessions = byTool['gemini'] ?? [];
+ * ```
+ *
+ * @example
+ * ```tsx
+ * // Filter by tool
+ * const { sessions } = useNativeSessions({ tool: 'gemini' });
+ * ```
+ */
+export function useNativeSessions(
+  options: UseNativeSessionsOptions = {}
+): UseNativeSessionsReturn {
+  const { tool, staleTime = STALE_TIME, gcTime = GC_TIME, enabled = true } = options;
+  const projectPath = useWorkflowStore(selectProjectPath);
+
+  const query = useQuery<NativeSessionsListResponse>({
+    queryKey: workspaceQueryKeys.nativeSessionsList(projectPath, tool),
+    queryFn: () => fetchNativeSessions(tool, projectPath),
+    staleTime,
+    gcTime,
+    enabled,
+    refetchOnWindowFocus: false,
+    retry: 2,
+    retryDelay: (attemptIndex) => Math.min(1000 * 2 ** attemptIndex, 10000),
+  });
+
+  // Memoize sessions and byTool calculations
+  const { sessions, byTool } = React.useMemo(() => {
+    const sessions = query.data?.sessions ?? [];
+    const byTool = groupByTool(sessions);
+    return { sessions, byTool };
+  }, [query.data]);
+
+  const refetch = async () => {
+    await query.refetch();
+  };
+
+  return {
+    sessions,
+    byTool,
+    count: query.data?.count ?? 0,
+    isLoading: query.isLoading,
+    isFetching: query.isFetching,
+    error: query.error,
+    refetch,
+  };
+}