feat: Device snapshot delete api (gkd-kit#1294)

### **快照删除 API 详情**

* **请求地址**: `http://[手机IP]:[端口]/api/deleteSnapshot`
* **请求方法**: `POST`
* **请求头**: `Content-Type: application/json`
* **请求体 (JSON)**:
```json
{
  "id": 123456789
}

```

*(注：`id` 为长整型数字，不加引号)*
* **预期响应**:
```json
{
  "message": "快照删除成功"
}

```

Author: cjy0812

app/src/main/kotlin/li/songe/gkd/service/HttpService.kt

@@ -214,6 +214,18 @@ private fun CoroutineScope.createServer(port: Int) = embeddedServer(CIO, port) {
                 }
                 call.respond(list)
             }
+            post("/deleteSnapshot") {
+                val data = call.receive<ReqId>()
+                val allSnapshots = DbSet.snapshotDao.query().first()
+                val snapshot = allSnapshots.find { it.id == data.id }
+                if (snapshot != null) {
+                    SnapshotExt.removeSnapshot(data.id)
+                    DbSet.snapshotDao.delete(snapshot)
+                    call.respond(RpcOk("快照删除成功"))
+                } else {
+                    throw RpcError("快照不存在或已被删除")
+                }
+            }
             post("/updateSubscription") {
                 val subscription =
                     RawSubscription.parse(call.receiveText(), json5 = false)