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/runtime/tests/node-half.client.spec.ts

@@ -0,0 +1,10 @@
+/** Node half: the empty host apply (Loader governance + dsh.client discovery placeholder). */
+import { describe, expect, it } from 'vitest'
+import { apply } from '../src/index.ts'
+
+describe('node half', () => {
+  it('apply is a no-op host placeholder', () => {
+    apply(undefined)
+    expect(true).toBe(true) // reaching here without throw is the contract
+  })
+})