test(singlefile): update error count expectation for enhanced validation

Adjust invalid agent test to expect 3 errors instead of 2, reflecting the addition of CUE concreteness validation alongside existing Go-based checks.

Author: Test User

internal/cli/singlefile_test.go

@@ -326,7 +326,7 @@ No name or description.
 		wantErr     bool // Expect error to be returned (not in results)
 	}{
 		{"valid agent", validAgent, "", true, 0, false},
-		{"invalid agent", invalidAgent, "", false, 2, false}, // Missing name and description
+		{"invalid agent", invalidAgent, "", false, 3, false}, // Missing name and description (CUE + Go checks)
 		{"nonexistent", filepath.Join(tmpDir, "nope.md"), "", false, 0, true},
 	}