feat: Add UNKNOWN to TPU node state, This state will be used to prevent a node from being marked as READY during diagnose after it has failed repair

.jsdoc.js

@@ -1,4 +1,4 @@
-// Copyright 2024 Google LLC
+// Copyright 2025 Google LLC
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -40,7 +40,7 @@ module.exports = {
     includePattern: '\\.js$'
   },
   templates: {
-    copyright: 'Copyright 2024 Google LLC',
+    copyright: 'Copyright 2025 Google LLC',
     includeDate: false,
     sourceFiles: false,
     systemName: '@google-cloud/spanner',

protos/google/spanner/admin/instance/v1/common.proto

@@ -17,6 +17,7 @@ syntax = "proto3";
 package google.spanner.admin.instance.v1;
 
 import "google/api/field_behavior.proto";
+import "google/api/resource.proto";
 import "google/protobuf/timestamp.proto";
 
 option csharp_namespace = "Google.Cloud.Spanner.Admin.Instance.V1";

protos/google/spanner/v1/type.proto

@@ -175,6 +175,10 @@ enum TypeCode {
   // For example, `P1Y2M3DT4H5M6.5S` represents time duration of 1 year, 2
   // months, 3 days, 4 hours, 5 minutes, and 6.5 seconds.
   INTERVAL = 16;
+
+  // Encoded as `string`, in lower-case hexa-decimal format, as described
+  // in RFC 9562, section 4.
+  UUID = 17;
 }
 
 // `TypeAnnotationCode` is used as a part of [Type][google.spanner.v1.Type] to