refactor(gui): copy-free settings shell; ui-settings-general owns ownerless copy

The shell is now a pure composition face: no dictionaries, no locale
dependency, and three new chrome content seats (settings.trigger /
settings.header / settings.close) whose slot content also carries the
accessible names (trigger text, dialog aria-labelledby, visually hidden
close label). ui-settings-general returns as the owner of copy that
belongs to no single feature: chrome content, the General section with
its item slot, and the settings dictionaries. Slot types split homes —
trigger/header/close/section live in the shell contract; the
settings.general.item entry moves to the locale package (the common
dependency of every item registrant), with ui-theme consuming it
through a re-export seam; the verbatim duplicate merges are gone and
the dependency graph is a clean DAG.

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

@@ -0,0 +1,18 @@
+import { describe, expect, it } from 'vitest'
+import { Context } from 'cordis'
+import * as GeneralInvariant from '@deepseek-ai/dsh-client-ui-settings-general/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(GeneralInvariant).await()).resolves.toBeDefined()
+  })
+
+  it('node-half apply is a no-op host placeholder', async () => {
+    const { apply } = await import('@deepseek-ai/dsh-client-ui-settings-general')
+    apply()
+    expect(true).toBe(true) // reaching here without throw is the contract
+  })
+})