实现插件配置持久化与任务队列持久化

插件配置持久化：
- plugin_settings 表新增 config_json 字段，支持存储每个插件的自定义配置
- BaseCrawlerPlugin 新增 default_config 属性和 update_config 方法
- PluginSettingsRepository 新增 get_config / set_config 方法
- PluginService 新增 get_plugin_config 和 update_plugin_config
- api/routes/plugins.py 新增 GET /{id}/config 和 POST /{id}/config 接口
- 前端 Plugins.vue 增加配置编辑对话框，支持动态渲染数字/布尔/字符串类型配置
- ip3366 插件示例化：增加 max_pages 配置项，验证配置生效后会动态更新爬取 URL

任务队列持久化：
- 新建 validation_tasks 表：id, ip, port, protocol, status, result, response_time_ms, created_at, updated_at
- 新建 ValidationTaskRepository，提供 insert_batch / acquire_pending / complete_task / reset_processing 等方法
- ValidationQueue 重构：
  - submit() 时把任务写入数据库并唤醒 Worker
  - Worker 通过 acquire_pending 原子取任务并验证
  - 验证完成后更新任务状态并入库有效代理
  - 启动时自动恢复之前中断的 processing 任务为 pending
  - 支持 drain() 等待所有 pending 完成
- 调度器验证流程同样自动持久化到任务表

其他适配：
- 更新 api/deps.py 和 api/lifespan.py，移除对已删除 settings_service 的残留引用
- 更新前端 pluginService.js 和 api/index.js 增加配置相关 API

repositories/task_repo.py

@@ -0,0 +1,135 @@
+"""验证任务队列持久化层"""
+import aiosqlite
+from typing import List, Optional
+from models.domain import ProxyRaw
+from core.log import logger
+
+
+class ValidationTaskRepository:
+    """验证任务 Repository —— 支持队列持久化"""
+
+    @staticmethod
+    async def insert_batch(db: aiosqlite.Connection, proxies: List[ProxyRaw]) -> int:
+        if not proxies:
+            return 0
+        try:
+            rows = [(p.ip, p.port, p.protocol) for p in proxies]
+            await db.executemany(
+                """
+                INSERT INTO validation_tasks (ip, port, protocol, status, created_at)
+                VALUES (?, ?, ?, 'pending', CURRENT_TIMESTAMP)
+                """,
+                rows,
+            )
+            await db.commit()
+            return len(rows)
+        except Exception as e:
+            logger.error(f"insert_batch validation tasks failed: {e}")
+            return 0
+
+    @staticmethod
+    async def acquire_pending(db: aiosqlite.Connection) -> Optional[dict]:
+        """原子性地获取一个 pending 任务并将其标记为 processing"""
+        try:
+            async with db.execute(
+                """
+                SELECT id, ip, port, protocol FROM validation_tasks
+                WHERE status = 'pending'
+                ORDER BY id ASC
+                LIMIT 1
+                """
+            ) as cursor:
+                row = await cursor.fetchone()
+                if not row:
+                    return None
+                task_id = row[0]
+                await db.execute(
+                    "UPDATE validation_tasks SET status = 'processing', updated_at = CURRENT_TIMESTAMP WHERE id = ?",
+                    (task_id,),
+                )
+                await db.commit()
+                return {"id": task_id, "ip": row[1], "port": row[2], "protocol": row[3]}
+        except Exception as e:
+            logger.error(f"acquire_pending failed: {e}")
+            return None
+
+    @staticmethod
+    async def complete_task(
+        db: aiosqlite.Connection,
+        task_id: int,
+        is_valid: bool,
+        response_time_ms: Optional[float] = None,
+    ) -> bool:
+        try:
+            await db.execute(
+                """
+                UPDATE validation_tasks
+                SET status = 'completed',
+                    result = ?,
+                    response_time_ms = ?,
+                    updated_at = CURRENT_TIMESTAMP
+                WHERE id = ?
+                """,
+                ("valid" if is_valid else "invalid", response_time_ms, task_id),
+            )
+            await db.commit()
+            return True
+        except Exception as e:
+            logger.error(f"complete_task failed: {e}")
+            return False
+
+    @staticmethod
+    async def fail_task(db: aiosqlite.Connection, task_id: int) -> bool:
+        try:
+            await db.execute(
+                """
+                UPDATE validation_tasks
+                SET status = 'failed',
+                    result = 'invalid',
+                    updated_at = CURRENT_TIMESTAMP
+                WHERE id = ?
+                """,
+                (task_id,),
+            )
+            await db.commit()
+            return True
+        except Exception as e:
+            logger.error(f"fail_task failed: {e}")
+            return False
+
+    @staticmethod
+    async def get_pending_count(db: aiosqlite.Connection) -> int:
+        async with db.execute(
+            "SELECT COUNT(*) FROM validation_tasks WHERE status = 'pending'"
+        ) as cursor:
+            row = await cursor.fetchone()
+            return row[0] if row else 0
+
+    @staticmethod
+    async def reset_processing(db: aiosqlite.Connection) -> int:
+        """将异常中断的 processing 任务重置为 pending，用于启动恢复"""
+        try:
+            await db.execute(
+                """
+                UPDATE validation_tasks
+                SET status = 'pending', updated_at = CURRENT_TIMESTAMP
+                WHERE status = 'processing'
+                """
+            )
+            await db.commit()
+            return db.total_changes
+        except Exception as e:
+            logger.error(f"reset_processing failed: {e}")
+            return 0
+
+    @staticmethod
+    async def cleanup_old(db: aiosqlite.Connection, days: int = 7) -> int:
+        try:
+            await db.execute(
+                "DELETE FROM validation_tasks WHERE updated_at < datetime('now', '-{} days')".format(days)
+            )
+            await db.commit()
+            return db.total_changes
+        except Exception as e:
+            logger.error(f"cleanup_old tasks failed: {e}")
+            return 0