全面架构重构：建立分层架构与高度可扩展的插件系统

后端重构：
- 新增分层架构：API Routes -> Services -> Repositories -> Infrastructure
- 彻底移除全局单例，全面采用 FastAPI 依赖注入
- 新增 api/ 目录拆分路由（proxies, plugins, scheduler, settings, stats）
- 新增 services/ 业务逻辑层：ProxyService, PluginService, SchedulerService, ValidatorService, SettingsService
- 新增 repositories/ 数据访问层：ProxyRepository, SettingsRepository, PluginSettingsRepository
- 新增 models/ 层：Pydantic Schemas + Domain Models
- 重写 core/config.py：采用 Pydantic Settings 管理配置
- 新增 core/db.py：基于 asynccontextmanager 的连接管理，支持数据库迁移
- 新增 core/exceptions.py：统一业务异常体系

插件系统重构（核心）：
- 新增 core/plugin_system/：BaseCrawlerPlugin + PluginRegistry
- 采用显式注册模式（装饰器 + plugins/__init__.py），类型安全、测试友好
- 新增 plugins/base.py：BaseHTTPPlugin 通用 HTTP 爬虫基类
- 迁移全部 7 个插件到新架构（fate0, proxylist_download, ip3366, ip89, kuaidaili, speedx, yundaili）
- 插件状态持久化到 plugin_settings 表

任务调度重构：
- 新增 core/tasks/queue.py：ValidationQueue + WorkerPool
- 解耦爬取与验证：爬虫只负责爬取，代理提交队列后由 Worker 异步验证
- 调度器定时从数据库拉取存量代理并分批投入验证队列

前端调整：
- 新增 frontend/src/services/ 层拆分 API 调用逻辑
- 调整 stores/ 和 views/ 使用 Service 层
- 保持 API 兼容性，页面无需大幅修改

其他：
- 新增 main.py 作为新入口
- 新增 DESIGN.md 架构设计文档
- 更新 requirements.txt 增加 pydantic-settings

plugins/ip3366.py

@@ -1,74 +1,51 @@
-import sys
-import os
-sys.path.append(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
-
-from core.crawler import BasePlugin
-from core.log import logger
-from bs4 import BeautifulSoup
 import re
-import asyncio
+from typing import List
+from bs4 import BeautifulSoup
+from core.plugin_system import ProxyRaw
+from plugins.base import BaseHTTPPlugin
+from core.log import logger
 
-VALID_PROTOCOLS = ['http', 'https', 'socks4', 'socks5']
+VALID_PROTOCOLS = ("http", "https", "socks4", "socks5")
+
+
+class Ip3366Plugin(BaseHTTPPlugin):
+    name = "ip3366"
+    display_name = "IP3366"
+    description = "从 IP3366 网站爬取免费代理"
 
-class Ip3366Plugin(BasePlugin):
     def __init__(self):
         super().__init__()
-        self.name = "IP3366"
-        # 抓取高匿和普通代理的前 5 页
         self.urls = [
             f"http://www.ip3366.net/free/?stype=1&page={i}" for i in range(1, 6)
         ] + [
             f"http://www.ip3366.net/free/?stype=2&page={i}" for i in range(1, 6)
         ]
 
-    async def parse(self, html):
-        if not html:
-            return
-            
-        soup = BeautifulSoup(html, 'lxml')
-        list_div = soup.find('div', id='list')
-        if not list_div: return
-        
-        table = list_div.find('table')
-        if not table: return
+    async def crawl(self) -> List[ProxyRaw]:
+        results = []
+        for url in self.urls:
+            html = await self.fetch(url, timeout=15)
+            if not html:
+                continue
+            soup = BeautifulSoup(html, "lxml")
+            list_div = soup.find("div", id="list")
+            if not list_div:
+                continue
+            table = list_div.find("table")
+            if not table:
+                continue
 
-        rows = table.find_all('tr')
-        count = 0
-        for row in rows:
-            tds = row.find_all('td')
-            if len(tds) >= 5:
-                ip = tds[0].get_text(strip=True)
-                port = tds[1].get_text(strip=True)
-                protocol = tds[4].get_text(strip=True).lower() if len(tds) > 4 else 'http'
-                
-                if protocol not in VALID_PROTOCOLS:
-                    protocol = 'http'
-                
-                if re.match(r'^\d+\.\d+\.\d+\.\d+$', ip) and port.isdigit():
-                    yield ip, int(port), protocol
-                    count += 1
-        
-        if count > 0:
-            logger.info(f"{self.name} 解析完成，获得 {count} 个潜在代理")
+            for row in table.find_all("tr"):
+                tds = row.find_all("td")
+                if len(tds) >= 5:
+                    ip = tds[0].get_text(strip=True)
+                    port = tds[1].get_text(strip=True)
+                    protocol = tds[4].get_text(strip=True).lower() if len(tds) > 4 else "http"
+                    if protocol not in VALID_PROTOCOLS:
+                        protocol = "http"
+                    if re.match(r"^\d+\.\d+\.\d+\.\d+$", ip) and port.isdigit():
+                        results.append(ProxyRaw(ip, int(port), protocol))
 
-
-if __name__ == "__main__":
-    async def test_plugin():
-        plugin = Ip3366Plugin()
-        print(f"========== 测试 {plugin.name} ==========")
-        print(f"目标URL数量: {len(plugin.urls)}")
-        print(f"开始抓取...\n")
-        
-        proxies = await plugin.run()
-        
-        print(f"\n========== 抓取结果 ==========")
-        print(f"总计获取 {len(proxies)} 个代理:")
-        print("-" * 60)
-        
-        for idx, (ip, port, protocol) in enumerate(proxies, 1):
-            print(f"{idx:3d}. {ip:15s} : {str(port):5s}  |  {protocol}")
-        
-        print("-" * 60)
-        print(f"完成！共 {len(proxies)} 个代理~")
-    
-    asyncio.run(test_plugin())
+        if results:
+            logger.info(f"{self.display_name} 解析完成，获得 {len(results)} 个潜在代理")
+        return results