refactor(commands): move the command service to Remote

`CommandService.list` and `execute` carry the wire contract directly through
`@Remote`, and the Client assembly mounts the generated commands
contribution. The legacy API Proxy route, its schemas, the map rows, the
generated client methods and the fixture's command domain are removed, so the
catalog and the admission call have one owner again.

`Session.command()` keeps a result-shaped public face for parity with the
prompt, cancel and attachment neighbours it sits beside, and reads the
generated namespace through one `SessionRemotes` parameter. The Session
cluster declares that face against the owning business package rather than the
generated contribution: the Host compiler aggregate builds this package, and
it runs before any contribution is emitted.

Migrated calls lose the `title-invalid` class of protocol-only error codes and
report `internal`; no production caller branched on them.

packages/api/remotes/src/client/index.ts

@@ -1,10 +1,12 @@
 /** Platform-neutral assembly of generated Host Remote contributions. */
 
 import type { Context } from '@deepseek-ai/cordis'
+import commandsRemote from '@deepseek-ai/dsh-commands/remote'
 import goalsRemote from '@deepseek-ai/dsh-goal/remote'
 import type { TypeRTClientRemote } from '@deepseek-ai/dsh-type-meta'
 
 export type { TypeRTClientRemote as ClientRemote } from '@deepseek-ai/dsh-type-meta'
+export type {} from '@deepseek-ai/dsh-commands/remote'
 export type {} from '@deepseek-ai/dsh-goal/remote'
 // The forwarded-event allowlist's selection seat: without it in the consumer's
 // compilation face `TypeRTRemoteEvent` is `never` and every `$on` call fails.
@@ -17,12 +19,22 @@ export type {} from '@deepseek-ai/dsh-credentials/types'
 export type {} from '@deepseek-ai/dsh-llm/types'
 export type {} from '@deepseek-ai/dsh-agent-presets/types'
 export type {} from '@deepseek-ai/dsh-settings/types'
+
 /**
- * The Gateway Client face's own declaration merges, type-only: `ctx.remote` and
- * with it the `$on`/`$dispatch` surface. Erased at emit, so this facade still
- * carries no runtime edge to the Gateway implementation.
+ * The carrier's Client-facing types, re-exported so a business package names one
+ * assembly package instead of both this facade and the Connection plugin. Type-only:
+ * the carrier's runtime values stay behind their own module edge.
  */
-export type {} from '@deepseek-ai/dsh-api-gateway/client'
+export type {
+  ClientResponse, ConfigurableProviderView, ConnectionHandle, ConnectionSinks, ContentBlock,
+  CredentialView, DirectoryListing, DiscoveredModelView, HistoryEntry, HostFrame, IApiClient,
+  MessageId, ModelCatalogFailure, ModelProviderGroup, ModelReasoningEffort, ModelSelection,
+  MuxFrame, PromptContentPart, QuestionResponsePayload, QueueAction, RpcError, RpcId, RpcReceipt,
+  RpcRequest, RpcResponse, RpcResult, SessionId, SessionModels, SessionSearchItem,
+  SessionSummary, SettingsNamespaceView, SettingsPathOpView, SkillEntry, StreamChunk,
+  SubagentAddress, SubagentCatalog, TaskView, ToolCallView, ToolEventView, ToolResultView,
+  WorkspaceId, WorkspaceView
+} from '@deepseek-ai/dsh-client-connection/client'
 
 declare module '@deepseek-ai/cordis' {
   interface Context {
@@ -40,5 +52,16 @@ export const inject = ['remote']
  * @returns disposer after every selected Remote namespace is ready.
  */
 export async function apply(ctx: Context): Promise<() => Promise<void>> {
-  return await ctx.remote.$mount(goalsRemote)
+  const disposers: Array<() => Promise<void>> = []
+  try {
+    for (const contribution of [commandsRemote, goalsRemote]) {
+      disposers.push(await ctx.remote.$mount(contribution))
+    }
+  } catch (error) {
+    for (const dispose of disposers.reverse()) await dispose()
+    throw error
+  }
+  return async () => {
+    for (const dispose of disposers.reverse()) await dispose()
+  }
 }