Add getConfigSchema to surface adapter config fields in UI

- src/server/config-schema.ts: define schema with Core, Kubernetes,
  and Operational field groups matching agentConfigurationDoc
- src/server/config-schema.test.ts: 10 tests covering field types,
  defaults, options, and group structure
- src/server/index.ts: attach getConfigSchema to ServerAdapterModule
- Revert k8s-client.ts loadFromConfig change (not available in installed
  @kubernetes/client-node version)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/server/index.ts

@@ -3,6 +3,7 @@ import { type, models, agentConfigurationDoc } from "../index.js";
 import { execute } from "./execute.js";
 import { testEnvironment } from "./test.js";
 import { sessionCodec } from "./session.js";
+import { getConfigSchema } from "./config-schema.js";
 
 export function createServerAdapter(): ServerAdapterModule {
   return {
@@ -13,7 +14,8 @@ export function createServerAdapter(): ServerAdapterModule {
     models,
     supportsLocalAgentJwt: true,
     agentConfigurationDoc,
-  };
+    getConfigSchema,
+  } as ServerAdapterModule;
 }
 
 export { execute, testEnvironment, sessionCodec };