test(gui): settings package suites; ledger-judged re-registration

Full per-file coverage for the three settings packages: invariant
companions, store mirroring with revision guards, behavior-shaped
section/shell specs (props-fed, real store engine), and apply-level
suites on a real Context + SlotCore covering declaration-aware deferral
and HMR collapse recovery. All three registrants now judge presence on
the slot ledger instead of a local disposer, which went stale when a
parent redeclaration cascade removed the entry (ds-review-bot finding);
the locale re-register path keeps the same idempotence.

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

@@ -0,0 +1,18 @@
+import { describe, expect, it } from 'vitest'
+import { Context } from 'cordis'
+import * as SettingsInvariant from '@deepseek-ai/dsh-client-ui-settings/invariant'
+import InvariantService from '@deepseek-ai/dsh-invariants'
+
+describe('invariant companion', () => {
+  it('registers under the package name with an empty installer', async () => {
+    const ctx = new Context()
+    await ctx.plugin(InvariantService, { enabled: true })
+    await expect(ctx.plugin(SettingsInvariant).await()).resolves.toBeDefined()
+  })
+
+  it('node-half apply is a no-op host placeholder', async () => {
+    const { apply } = await import('@deepseek-ai/dsh-client-ui-settings')
+    apply()
+    expect(true).toBe(true) // reaching here without throw is the contract
+  })
+})