fix(ci): align plugin inventory with current contracts

packages/client/ui-plugins/tests/invariant.client.spec.ts

@@ -0,0 +1,15 @@
+import { Context } from '@deepseek-ai/cordis'
+import { describe, expect, it } from 'vitest'
+import InvariantService from '@deepseek-ai/dsh-invariants'
+import * as PluginsInvariant from '../src/invariant.ts'
+
+describe('ui-plugins invariant companion', () => {
+  it('registers the empty installer and keeps the node half inert', async () => {
+    const ctx = new Context()
+    await ctx.plugin(InvariantService, { enabled: true })
+    await expect(ctx.plugin(PluginsInvariant).await()).resolves.toBeDefined()
+    const { apply } = await import('../src/index.ts')
+    apply()
+    await ctx.fiber.dispose()
+  })
+})