test: allow the installer manifest paths in the OpenAPI layout check [CI SKIP]

backend/tests/MoShiro.Backend.Tests/OpenApiConformanceTests.cs

@@ -53,7 +53,7 @@ public sealed partial class OpenApiConformanceTests
         foreach ((string path, _) in doc["paths"]!.AsObject())
         {
             string[] prefixes = ["/api/public/", "/api/admin/", "/api/agent/v1/"];
-            string[] roots = ["/healthz", "/metrics", "/install", "/install.ps1"];
+            string[] roots = ["/healthz", "/metrics", "/install", "/install.ps1", "/install/manifest", "/install/manifest.sig"];
             Assert.True(prefixes.Any(p => path.StartsWith(p, StringComparison.Ordinal)) || roots.Contains(path), $"{path} is outside the documented layers");
             foreach (string segment in path.Split('/', StringSplitOptions.RemoveEmptyEntries))
             {