refactor: 全面重构核心架构，消除反复修改的根因

- 删除 ValidationQueue 双轨持久化队列，替换为纯内存 AsyncWorkerPool
- 引入统一后台任务框架 JobExecutor（Job/CrawlJob/ValidateAllJob）
- 新增 PluginRunner 统一插件执行（超时、重试、健康检查、统计）
- 重构 SchedulerService 职责收敛为仅定时触发 ValidateAllJob
- 使用 AsyncExitStack 重构 lifespan，安全管理长生命周期资源
- 路由层瘦身 50%+，业务异常上抛由全局中间件统一处理
- 实现设置全热更新（WorkerPool 并发、Validator 超时即时生效）
- 前端 Store 强制写后重新拉取，消除乐观更新数据不同步
- 删除 queue.py / task_repo.py / task_service.py
- 新增 execution 单元测试，全部 85 个测试通过

app/core/execution/job.py

@@ -0,0 +1,159 @@
+"""Job 定义 - 所有后台异步任务的统一抽象"""
+import uuid
+from abc import ABC, abstractmethod
+from dataclasses import dataclass, field
+from datetime import datetime
+from enum import Enum
+from typing import Any, Dict, List, Optional
+
+from app.models.domain import ProxyRaw
+
+
+class JobStatus(Enum):
+    PENDING = "pending"
+    RUNNING = "running"
+    COMPLETED = "completed"
+    FAILED = "failed"
+    CANCELLED = "cancelled"
+
+
+@dataclass
+class Job(ABC):
+    """后台任务基类"""
+
+    id: str = field(default_factory=lambda: str(uuid.uuid4()))
+    status: JobStatus = JobStatus.PENDING
+    progress: float = 0.0  # 0-100
+    result: Any = None
+    error: Optional[str] = None
+    created_at: datetime = field(default_factory=datetime.now)
+    updated_at: datetime = field(default_factory=datetime.now)
+    _cancelled: bool = field(default=False, repr=False)
+
+    def cancel(self) -> None:
+        """请求取消任务"""
+        self._cancelled = True
+        if self.status in (JobStatus.PENDING, JobStatus.RUNNING):
+            self.status = JobStatus.CANCELLED
+            self._touch()
+
+    def _touch(self) -> None:
+        self.updated_at = datetime.now()
+
+    def _set_running(self) -> None:
+        self.status = JobStatus.RUNNING
+        self._touch()
+
+    def _set_completed(self, result: Any = None) -> None:
+        self.status = JobStatus.COMPLETED
+        self.result = result
+        self.progress = 100.0
+        self._touch()
+
+    def _set_failed(self, error: str) -> None:
+        self.status = JobStatus.FAILED
+        self.error = error
+        self._touch()
+
+    @property
+    def is_cancelled(self) -> bool:
+        return self._cancelled
+
+    @abstractmethod
+    async def run(self) -> Any:
+        """执行任务的核心逻辑，子类必须实现"""
+        raise NotImplementedError
+
+    def to_dict(self) -> Dict[str, Any]:
+        return {
+            "id": self.id,
+            "status": self.status.value,
+            "progress": round(self.progress, 2),
+            "result": self.result,
+            "error": self.error,
+            "created_at": self.created_at.isoformat(),
+            "updated_at": self.updated_at.isoformat(),
+        }
+
+
+@dataclass
+class CrawlJob(Job):
+    """插件爬取任务"""
+
+    plugin_id: str = ""
+    plugin_runner: Any = field(repr=False, default=None)
+    proxy_service: Any = field(repr=False, default=None)
+    validator_pool: Any = field(repr=False, default=None)
+
+    async def run(self) -> Dict[str, Any]:
+        from app.services.plugin_service import PluginService
+        from app.core.log import logger
+
+        self._set_running()
+        if not self.plugin_runner:
+            raise RuntimeError("plugin_runner is not set")
+
+        plugin_service = self.proxy_service or PluginService()
+        plugin = plugin_service.get_plugin(self.plugin_id)
+        if not plugin:
+            raise ValueError(f"Plugin '{self.plugin_id}' not found")
+
+        result = await self.plugin_runner.run(plugin)
+        proxies: List[ProxyRaw] = result.proxies if result else []
+
+        if proxies and self.validator_pool:
+            await self.validator_pool.submit(proxies)
+            logger.info(f"CrawlJob {self.id}: submitted {len(proxies)} proxies for validation")
+
+        payload = {
+            "plugin_id": self.plugin_id,
+            "proxy_count": len(proxies),
+        }
+        if result:
+            payload["success_count"] = result.success_count
+            payload["failure_count"] = result.failure_count
+        self._set_completed(payload)
+        return payload
+
+
+@dataclass
+class ValidateAllJob(Job):
+    """全量验证任务 - 验证数据库中所有存量代理"""
+
+    proxy_repo: Any = field(repr=False, default=None)
+    validator_pool: Any = field(repr=False, default=None)
+    batch_size: int = 100
+
+    async def run(self) -> Dict[str, Any]:
+        from app.repositories.proxy_repo import ProxyRepository
+        from app.core.db import get_db
+        from app.core.log import logger
+
+        self._set_running()
+        repo = self.proxy_repo or ProxyRepository()
+
+        async with get_db() as db:
+            proxies = await repo.list_all(db)
+
+        if not proxies:
+            self._set_completed({"total": 0, "submitted": 0})
+            return self.result
+
+        total = len(proxies)
+        submitted = 0
+        for i in range(0, total, self.batch_size):
+            if self.is_cancelled:
+                logger.info(f"ValidateAllJob {self.id}: cancelled")
+                break
+            batch = proxies[i : i + self.batch_size]
+            raws = [ProxyRaw(p.ip, p.port, p.protocol) for p in batch]
+            if self.validator_pool:
+                await self.validator_pool.submit(raws)
+            submitted += len(raws)
+            self.progress = min(100.0, (submitted / total) * 100)
+            self._touch()
+
+        payload = {"total": total, "submitted": submitted}
+        self._set_completed(payload)
+        logger.info(f"ValidateAllJob {self.id}: submitted {submitted}/{total} proxies")
+        return payload