refactor(backend): 将Celery替换为Arq进行协程任务处理

本次提交将后端的任务队列系统从Celery迁移到了Arq，以支持基于协程的任务处理。主要改动包括：
- 更新文档和配置文件，反映架构变化。
- 修改健康检查和服务初始化逻辑，以适应Arq的使用。
- 移除与Celery相关的代码，并添加Arq任务定义和调度器。
- 更新Dockerfile和相关脚本，确保Arq worker能够正确运行。
- 调整API和业务服务中的任务处理逻辑，移除对Celery的依赖。

这些改动旨在提高系统的异步处理能力和整体性能。

CLAUDE.md

@@ -16,6 +16,7 @@ This file provides guidance to Claude Code (claude.ai/code) when working with co
 ### Backend (FastAPI)
 - `cd backend && uv sync` - Install dependencies with UV
 - `cd backend && uv run python app/main.py` - Run development server
+- `cd backend && uv run python scripts/start_arq_worker.py` - Start ARQ worker
 - `cd backend && uv run pytest` - Run tests
 - `cd backend && uv run black .` - Format code with Black
 - `cd backend && uv run isort .` - Sort imports with isort
@@ -47,11 +48,11 @@ This is a full-stack application with:
 
 ### Backend Architecture
 - **Framework**: FastAPI with async/await
-- **Architecture**: Distributed microservices with Celery task queues
+- **Architecture**: Distributed microservices with ARQ task queues
 - **Browser Automation**: Playwright for web scraping
 - **Database**: PostgreSQL with asyncpg
 - **Cache**: Redis for distributed locking and state management
-- **Task Queue**: Celery with Redis broker
+- **Task Queue**: ARQ with Redis broker
 - **Monitoring**: OpenTelemetry integration
 - **Package Manager**: UV (configured in pyproject.toml)
 
@@ -77,7 +78,7 @@ This is a full-stack application with:
 - `app/models/` - SQLAlchemy data models
 - `app/schemas/` - Pydantic schemas
 - `app/services/` - Business logic services
-- `app/tasks/` - Celery task definitions
+- `app/tasks/` - ARQ task definitions
 - `app/repositories/` - Data access layer
 - `deploy/` - Docker and deployment configurations
 - `docs/` - Architecture and project documentation
@@ -96,7 +97,7 @@ This is a full-stack application with:
 #### Backend Features
 - Distributed web scraping with Playwright
 - Redis-based distributed locking
-- Celery task queue system
+- ARQ task queue system
 - Automatic task recovery and failure handling
 - Kubernetes deployment support
 - Graceful shutdown handling
@@ -120,7 +121,7 @@ This is a full-stack application with:
 #### Backend State
 - **Database**: PostgreSQL with SQLAlchemy ORM
 - **Cache**: Redis for distributed state and locking
-- **Task State**: Celery backend for task progress tracking
+- **Task State**: ARQ backend for task progress tracking
 - **Session State**: Redis-based session management
 
 ### Deployment Configuration
@@ -160,7 +161,7 @@ This is a full-stack application with:
 #### Key Architectural Patterns
 - **Microservices**: Backend uses service-oriented architecture
 - **Distributed Systems**: Redis-based coordination and locking
-- **Event-Driven**: Celery task queues for async processing
+- **Event-Driven**: ARQ task queues for async processing
 - **Reactive UI**: Frontend uses real-time updates with polling
 - **Type Safety**: Full TypeScript coverage on both ends