feat: 加固运行期可靠性并补齐调度与观测接口

- 运行句柄按 run_id 归属，修复取消后重跑时闸门被旧运行删除的竞态
- 调度循环改用取消令牌退出，启动时对账遗留运行，校验 rows_affected
- 三类任务统一参与调度，新增 /api/v1/stats 与 /api/v1/schedule
- SQLite 启用 WAL 与 busy_timeout，日志清理跳过活跃文件，单行上限 256 KiB
- 前端缓存管理令牌并在 403 时重试一次，仪表盘改用统计接口

frontend/src/api/generated.ts

@@ -132,6 +132,22 @@ export interface paths {
         patch?: never;
         trace?: never;
     };
+    "/api/v1/schedule": {
+        parameters: {
+            query?: never;
+            header?: never;
+            path?: never;
+            cookie?: never;
+        };
+        get: operations["list_schedule"];
+        put?: never;
+        post?: never;
+        delete?: never;
+        options?: never;
+        head?: never;
+        patch?: never;
+        trace?: never;
+    };
     "/api/v1/session": {
         parameters: {
             query?: never;
@@ -148,6 +164,22 @@ export interface paths {
         patch?: never;
         trace?: never;
     };
+    "/api/v1/stats": {
+        parameters: {
+            query?: never;
+            header?: never;
+            path?: never;
+            cookie?: never;
+        };
+        get: operations["task_stats"];
+        put?: never;
+        post?: never;
+        delete?: never;
+        options?: never;
+        head?: never;
+        patch?: never;
+        trace?: never;
+    };
     "/api/v1/system/directories": {
         parameters: {
             query?: never;
@@ -338,6 +370,15 @@ export interface components {
         RunStatus: "queued" | "running" | "succeeded" | "failed" | "timed_out" | "cancelled" | "skipped";
         /** @enum {string} */
         RunTrigger: "schedule" | "manual" | "retry";
+        /** @description 已注册调度的任务及其下次触发时间。 */
+        ScheduledTaskResponse: {
+            /**
+             * Format: date-time
+             * @description 下次触发时间；调度正在重建时可能为空
+             */
+            next_run_at?: string | null;
+            task_id: string;
+        };
         SessionResponse: {
             /** @description Random per-process token required for mutating browser requests. */
             token: string;
@@ -427,6 +468,39 @@ export interface components {
             task_id: string;
             trigger: components["schemas"]["RunTrigger"];
         };
+        /** @description 仪表盘指标：一次请求拿到全部计数，避免为每个指标各发一次列表查询。 */
+        TaskStatsResponse: {
+            /**
+             * Format: int64
+             * @description 已启用任务数
+             */
+            enabled: number;
+            /**
+             * Format: int64
+             * @description HTTP 类任务数
+             */
+            http: number;
+            /**
+             * Format: int64
+             * @description 进程类任务数
+             */
+            process: number;
+            /**
+             * Format: int64
+             * @description 当前正在执行的任务数
+             */
+            running: number;
+            /**
+             * Format: int64
+             * @description 脚本类任务数
+             */
+            script: number;
+            /**
+             * Format: int64
+             * @description 任务总数
+             */
+            total: number;
+        };
         UpdateTaskRequest: {
             action: components["schemas"]["TaskAction"];
             concurrency_policy?: components["schemas"]["ConcurrencyPolicy"];
@@ -718,6 +792,26 @@ export interface operations {
             };
         };
     };
+    list_schedule: {
+        parameters: {
+            query?: never;
+            header?: never;
+            path?: never;
+            cookie?: never;
+        };
+        requestBody?: never;
+        responses: {
+            /** @description Next trigger time per enabled task */
+            200: {
+                headers: {
+                    [name: string]: unknown;
+                };
+                content: {
+                    "application/json": components["schemas"]["ScheduledTaskResponse"][];
+                };
+            };
+        };
+    };
     session: {
         parameters: {
             query?: never;
@@ -738,6 +832,26 @@ export interface operations {
             };
         };
     };
+    task_stats: {
+        parameters: {
+            query?: never;
+            header?: never;
+            path?: never;
+            cookie?: never;
+        };
+        requestBody?: never;
+        responses: {
+            /** @description Dashboard counters */
+            200: {
+                headers: {
+                    [name: string]: unknown;
+                };
+                content: {
+                    "application/json": components["schemas"]["TaskStatsResponse"];
+                };
+            };
+        };
+    };
     list_directories: {
         parameters: {
             query?: {