Cloudreve Admin.Read OAuth tokens can trigger server-side node test requests

## Summary Cloudreve exposes two admin node test endpoints under the `Admin.Read` OAuth scope. These endpoints accept attacker-controlled node definitions and cause Cloudreve to make outbound server-side network requests. This allows an OAuth client authorized only for `Admin.Read` to trigger operational network actions that should require `Admin.Write`. ## Impact An attacker who obtains an admin-authorized OAuth token with `Admin.Read` but not `Admin.Write` can make the Cloudreve server connect to arbitrary URLs supplied in the request body. This can be used for blind SSRF, internal service probing, and triggering signed Cloudreve slave-style requests to attacker-chosen endpoints. ## Affected version Verified in source and runtime on latest master commit `ba2e870bbd17f1918dd2321de861e453f696d6a3` and latest observed tag `4.16.1`. ## Technical details The authenticated admin route group requires only `Admin.Read`: ```go auth := v4.Group("") auth.Use(middleware.LoginRequired()) auth.Use(middleware.RequiredScopes(types.ScopeAdminRead)) admin := auth.Group("admin", middleware.IsAdmin()) ``` The following routes are registered without `ScopeAdminWrite`: ```go node.POST("test", controllers.FromJSON[adminsvc.TestNodeService](adminsvc.TestNodeParamCtx{}), controllers.AdminTestSlave, ) node.POST("test/downloader", controllers.FromJSON[adminsvc.TestNodeDownloaderService](adminsvc.TestNodeDownloaderParamCtx{}), controllers.AdminTestDownloader, ) ``` By contrast, node create, update, an