test: update expectations for ZWSP-free object keys

- Add RFC 7230 compliance tests for object key validation
- Verify name field still contains ZWSP for core agents
- Update all test expectations to use getAgentDisplayName()

src/plugin-interface.test.ts

@@ -6,7 +6,7 @@ import { randomUUID } from "node:crypto"
 import { createPluginInterface } from "./plugin-interface"
 import { createAutoSlashCommandHook } from "./hooks/auto-slash-command"
 import { createStartWorkHook } from "./hooks/start-work"
-import { getAgentListDisplayName } from "./shared/agent-display-names"
+import { getAgentDisplayName } from "./shared/agent-display-names"
 import { readBoulderState } from "./features/boulder-state"
 import {
   _resetForTesting,