Fix task duplication: add single/multi-instance support with UI configuration and stop all running instances (#2837)

* Initial plan

* Stop running tasks before starting new scheduled instance

Co-authored-by: whyour <22700758+whyour@users.noreply.github.com>

* Add multi-instance support and fix stop to kill all running instances

- Add allow_multiple_instances field to Crontab model (default: 0 for single instance)
- Add validation for new field in commonCronSchema
- Add getAllPids and killAllTasks utility functions
- Update stop method to kill ALL running instances of a task
- Update runCron to respect allow_multiple_instances config
- Backward compatible: defaults to single instance mode

Co-authored-by: whyour <22700758+whyour@users.noreply.github.com>

* Add UI support for allow_multiple_instances configuration

- Add allow_multiple_instances field to ICrontab interface
- Add instance mode selector in task creation/edit modal
- Add translations for instance mode in Chinese and English
- Default to single instance mode for backward compatibility

Co-authored-by: whyour <22700758+whyour@users.noreply.github.com>

* Add allow_multiple_instances column migration and optimize db.ts

- Add allow_multiple_instances column to Crontabs table migration
- Refactor migration code to use data-driven approach
- Replace 11 individual try-catch blocks with single loop
- Improve code maintainability and readability

Co-authored-by: whyour <22700758+whyour@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: whyour <22700758+whyour@users.noreply.github.com>

back/shared/runCron.ts

@@ -2,10 +2,45 @@ import { spawn } from 'cross-spawn';
 import taskLimit from './pLimit';
 import Logger from '../loaders/logger';
 import { ICron } from '../protos/cron';
+import { CrontabModel, CrontabStatus } from '../data/cron';
+import { killTask } from '../config/util';
 
 export function runCron(cmd: string, cron: ICron): Promise<number | void> {
   return taskLimit.runWithCronLimit(cron, () => {
     return new Promise(async (resolve: any) => {
+      // Check if the cron is already running and stop it (only if multiple instances are not allowed)
+      try {
+        const existingCron = await CrontabModel.findOne({
+          where: { id: Number(cron.id) },
+        });
+
+        // Default to single instance mode (0) for backward compatibility
+        const allowMultipleInstances =
+          existingCron?.allow_multiple_instances === 1;
+
+        if (
+          !allowMultipleInstances &&
+          existingCron &&
+          existingCron.pid &&
+          (existingCron.status === CrontabStatus.running ||
+            existingCron.status === CrontabStatus.queued)
+        ) {
+          Logger.info(
+            `[schedule][停止已运行任务] 任务ID: ${cron.id}, PID: ${existingCron.pid}`,
+          );
+          await killTask(existingCron.pid);
+          // Update the status to idle after killing
+          await CrontabModel.update(
+            { status: CrontabStatus.idle, pid: undefined },
+            { where: { id: Number(cron.id) } },
+          );
+        }
+      } catch (error) {
+        Logger.error(
+          `[schedule][检查已运行任务失败] 任务ID: ${cron.id}, 错误: ${error}`,
+        );
+      }
+
       Logger.info(
         `[schedule][开始执行任务] 参数 ${JSON.stringify({
           ...cron,