test(apiproxy): drop the dead hostDescription fake override

363db89ba removed the client-side modality gate and the tests that fed
host.describe a scripted activeModel, but left the fakeApi override
field, its ResponseValue import, and the ?? fallback behind. Nothing
passes hostDescription, so the left arm was unreachable.

packages/host/apiproxy/tests/fetch-carrier.spec.ts

@@ -1,19 +1,13 @@
 import { CommandId } from '@deepseek-ai/dsh-commands/brand'
 import { describe, expect, it, vi } from 'vitest'
 import type { ApiProxy, HostFrame, MuxFrame } from '../src/api/index.ts'
-import type { ResponseValue } from '../src/api/rpc-map.ts'
 import type { ClientResponse, RpcMessage, RpcReceipt, RpcRequest } from '../src/api/rpc.ts'
 import { RpcId } from '../src/api/rpc.ts'
 import { toFetchHandler } from '../src/fetch/handler.ts'
 import { AbstractApiClient, InProcessApiClient } from '../src/fetch/client.ts'
 
 /** Minimal in-memory ApiProxy: echoes rpcIds, scripts one frame per stream. */
-function fakeApi(overrides: Partial<{
+function fakeApi(overrides: Partial<{ muxFrames: MuxFrame[]; hostFrames: HostFrame[]; crashOn: string }> = {}): ApiProxy {
-  muxFrames: MuxFrame[]
-  hostFrames: HostFrame[]
-  crashOn: string
-  hostDescription: ResponseValue<'host.describe'>
-}> = {}): ApiProxy {
   const muxFrames = overrides.muxFrames ?? [{ type: 'session/subscribed', sessionId: 's1' as never, lastSeq: -1 }]
   const hostFrames = overrides.hostFrames ?? [{ type: 'host/session-removed', sessionId: 's1' as never }]
   async function * stream<F>(frames: F[], signal: AbortSignal): AsyncGenerator<RpcRequest<F>> {
@@ -94,13 +88,7 @@ function fakeApi(overrides: Partial<{
     },
     host: {
       async describe(request) {
-        return {
+        return { rpcId: request.rpcId, result: { ok: true, value: { version: 'v', cwd: '/w', attachedSessions: 0 } } }
-          rpcId: request.rpcId,
-          result: {
-            ok: true,
-            value: overrides.hostDescription ?? { version: 'v', cwd: '/w', attachedSessions: 0 },
-          },
-        }
       },
       async pickDirectory(request) {
         return { rpcId: request.rpcId, result: { ok: true, value: { path: null } } }