refactor(client): name the compile face in every client test filename

A test file under packages/client now says which face it covers:
`*.client.spec.{ts,tsx}` and its `*.client.{ts,tsx}` helpers belong to the
Client aggregate, `*.host.spec.ts` to the host aggregate. The carrier's four
node-half specs take the Host suffix.

The two suffixes are mutually exclusive, so each aggregate excludes the
other's and both keep one broad test glob: `exclude` wins over `include`, and
`packages/client/**` no longer has to be excluded wholesale from the host
program with per-file `files` entries carved back out of it. A Host-face spec
that reaches only Host source therefore needs no cross-face project
reference, which the split-project rule rejects.

vitest still discovers every file through `**/*.spec.{ts,tsx}`.

packages/client/web/tests/app-shell.client.spec.tsx

@@ -0,0 +1,61 @@
+// @vitest-environment jsdom
+/**
+ * App-shell assembly plugin on the real machinery: bare Context + production
+ * SlotsService + the test-runtime session/workspace doubles. Deliberately NOT
+ * mounted through SlotTestRuntime — its create() installs the capturing
+ * renderer and install() is boot-once; app-shell IS the production installer,
+ * so this bench hands it the uninstalled service exactly as boot does.
+ */
+import { afterEach, describe, expect, it, vi } from 'vitest'
+import { act, cleanup, render } from '@testing-library/react'
+import { Context } from '@deepseek-ai/cordis'
+import { SlotsService } from '@deepseek-ai/dsh-client-runtime/client'
+import { TestSessions, TestWorkspaces } from '@deepseek-ai/dsh-client-test-runtime'
+import type { Stabilizer } from '@deepseek-ai/dsh-client-test-runtime'
+import * as AppShell from '@deepseek-ai/dsh-client-web/src/app-shell.ts'
+
+afterEach(cleanup)
+
+const stabilize: Stabilizer = async (fn) => { await act(async () => { await fn() }) }
+
+async function bench() {
+  const ctx = new Context()
+  await ctx.plugin(SlotsService).await()
+  const slots = ctx.get('slots') as SlotsService
+  ctx.provide('sessions', new TestSessions(stabilize, ctx))
+  ctx.provide('workspaces', new TestWorkspaces(stabilize))
+  ctx.provide('layout', { openDetails: vi.fn(), closeDetails: vi.fn() })
+  const fiber = ctx.plugin({ inject: [...AppShell.inject], apply: AppShell.apply })
+  await fiber.await()
+  return { ctx, slots, fiber }
+}
+
+describe('app-shell assembly plugin', () => {
+  it('installs the renderer and provides the assembled appShell face', async () => {
+    const { ctx, slots } = await bench()
+    slots.register({ name: 'root' }, () => <div data-testid="root-probe" />)
+    const shell = ctx.get('appShell')
+    expect(shell).toBeDefined()
+    const view = render(<>{shell!.renderApp()}</>)
+    expect(view.getByTestId('root-probe')).toBeTruthy()
+  })
+
+  it('assembles once: repeated renderApp calls reuse the built closure', async () => {
+    const { ctx, slots } = await bench()
+    slots.register({ name: 'root' }, () => <div data-testid="root-probe" />)
+    const shell = ctx.get('appShell')!
+    const first = render(<>{shell.renderApp()}</>)
+    expect(first.getByTestId('root-probe')).toBeTruthy()
+    first.unmount()
+    // Second call rides the cached closure (renderApp ??=) and still renders.
+    const second = render(<>{shell.renderApp()}</>)
+    expect(second.getByTestId('root-probe')).toBeTruthy()
+  })
+
+  it('fiber dispose retracts the service and uninstalls the renderer', async () => {
+    const { ctx, slots, fiber } = await bench()
+    await stabilize(() => fiber.dispose())
+    expect(ctx.get('appShell')).toBeUndefined()
+    expect(() => slots.renderSlot('root', {})).toThrow('not installed')
+  })
+})