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/conversation.client.spec.ts

@@ -0,0 +1,31 @@
+/** Assistant block classifier (moved here with sessions/conversation.ts). */
+
+import { describe, expect, it } from 'vitest'
+import { AttachmentId } from '@deepseek-ai/dsh-attachment'
+import type { ContentBlock } from '@deepseek-ai/dsh-api-remotes/client'
+import { toAssistantBlock, toAssistantBlocks } from '../src/client/sessions/conversation.ts'
+
+describe('toAssistantBlock', () => {
+  it('classifies the four block shapes', () => {
+    const attachment = {
+      attachmentId: AttachmentId(`sha256:${'a'.repeat(64)}`),
+      mediaType: 'image/png' as const,
+      bytes: 68,
+      width: 1,
+      height: 1,
+    }
+    const blocks: ContentBlock[] = [
+      { type: 'text', text: '正文' },
+      { type: 'reasoning', text: '思考' },
+      { type: 'tool-call', id: 'c1', name: 'echo', arguments: '{}' } as ContentBlock,
+      { type: 'image', attachment },
+    ]
+    expect(toAssistantBlocks(blocks)).toEqual([
+      { kind: 'text', text: '正文' },
+      { kind: 'reasoning', text: '思考' },
+      { kind: 'tool-call', callId: 'c1', name: 'echo', argsRaw: '{}' },
+      { kind: 'image', attachment },
+    ])
+    expect(toAssistantBlock(blocks[0] as ContentBlock)).toEqual({ kind: 'text', text: '正文' })
+  })
+})