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/components/shared/NativeSessionPanel.tsx

@@ -24,6 +24,7 @@ import {
 } from '@/components/ui/Dialog';
 import { useNativeSession } from '@/hooks/useNativeSession';
 import { SessionTimeline } from './SessionTimeline';
+import { getToolVariant } from '@/lib/cli-tool-theme';
 
 // ========== Types ==========
 
@@ -35,19 +36,6 @@ export interface NativeSessionPanelProps {
 
 // ========== Helpers ==========
 
-/**
- * Get badge variant for tool name
- */
-function getToolVariant(tool: string): 'default' | 'secondary' | 'outline' | 'success' | 'warning' | 'info' {
-  const variants: Record<string, 'default' | 'secondary' | 'outline' | 'success' | 'warning' | 'info'> = {
-    gemini: 'info',
-    codex: 'success',
-    qwen: 'warning',
-    opencode: 'secondary',
-  };
-  return variants[tool?.toLowerCase()] || 'secondary';
-}
-
 /**
  * Truncate a string to a max length with ellipsis
  */