chore(deploy): 加入服务看门狗脚本与 Windows 计划任务注册文件

- watchdog.ps1：每 2 分钟健康检查，Docker/DB/Redis/API/Grafana 任一
  不健康自动重启，连续 3 次失败发飞书告警，C 盘超 85% 也告警
- backend-watchdog-task.xml：开机触发、2 分钟循环的计划任务配置

deploy/backend-watchdog-task.xml

@@ -0,0 +1,32 @@
+<?xml version="1.0" encoding="UTF-16"?>
+<Task version="1.3" xmlns="http://schemas.microsoft.com/windows/2004/02/mit/task">
+  <RegistrationInfo>
+    <Description>FruitShorts backend watchdog: health check every 2 minutes and restart unhealthy services.</Description>
+  </RegistrationInfo>
+  <Principals>
+    <Principal id="Author">
+      <UserId>S-1-5-18</UserId>
+      <RunLevel>HighestAvailable</RunLevel>
+    </Principal>
+  </Principals>
+  <Settings>
+    <MultipleInstancesPolicy>IgnoreNew</MultipleInstancesPolicy>
+    <DisallowStartIfOnBatteries>false</DisallowStartIfOnBatteries>
+    <StopIfGoingOnBatteries>false</StopIfGoingOnBatteries>
+    <StartWhenAvailable>true</StartWhenAvailable>
+    <ExecutionTimeLimit>PT10M</ExecutionTimeLimit>
+  </Settings>
+  <Triggers>
+    <BootTrigger>
+      <Repetition>
+        <Interval>PT2M</Interval>
+      </Repetition>
+    </BootTrigger>
+  </Triggers>
+  <Actions Context="Author">
+    <Exec>
+      <Command>powershell.exe</Command>
+      <Arguments>-NoProfile -ExecutionPolicy Bypass -File "C:\Users\Administrator\Desktop\ReelShorts\FruitServer\deploy\watchdog.ps1" -ComposeDir "C:\Users\Administrator\Desktop\ReelShorts\FruitServer" -LogDir "C:\Users\Administrator\Desktop\ReelShorts\FruitServer\logs"</Arguments>
+    </Exec>
+  </Actions>
+</Task>