feat(apiproxy): workspace.archiveSession RPC and archived-sessions frame

workspace.archiveSession answers the full updated archive set;
workspace.list carries the set as the reconnect baseline; the host
stream pushes host/archived-sessions-changed full snapshots from the
domain/changed global-put branch (same posture as workspace-changed).
Unknown sessions map to the existing session-not-found code.

packages/host/apiproxy/src/fetch/client.ts

@@ -31,6 +31,7 @@ import {
   sessionUpdateQueueValueSchema,
 } from '../api/sessions.schema.ts'
 import {
+  workspaceArchiveSessionValueSchema,
   workspaceCreateValueSchema,
   workspaceDeleteValueSchema,
   workspaceInsertSessionBeforeValueSchema,
@@ -98,6 +99,7 @@ export interface IApiClient {
     rename(payload: RequestPayload<'workspace.rename'>, signal?: AbortSignal): Promise<RpcResponse<ResponseValue<'workspace.rename'>>>
     delete(payload: RequestPayload<'workspace.delete'>, signal?: AbortSignal): Promise<RpcResponse<ResponseValue<'workspace.delete'>>>
     insertSessionBefore(payload: RequestPayload<'workspace.insertSessionBefore'>, signal?: AbortSignal): Promise<RpcResponse<ResponseValue<'workspace.insertSessionBefore'>>>
+    archiveSession(payload: RequestPayload<'workspace.archiveSession'>, signal?: AbortSignal): Promise<RpcResponse<ResponseValue<'workspace.archiveSession'>>>
   }
   commands: {
     list(payload: RequestPayload<'command.list'>, signal?: AbortSignal): Promise<RpcResponse<ResponseValue<'command.list'>>>
@@ -163,6 +165,7 @@ const UNARY_VALUE_SCHEMAS: { [K in keyof RpcMethodMap]: z.ZodType<Wire<ResponseV
   'workspace.rename': workspaceRenameValueSchema,
   'workspace.delete': workspaceDeleteValueSchema,
   'workspace.insertSessionBefore': workspaceInsertSessionBeforeValueSchema,
+  'workspace.archiveSession': workspaceArchiveSessionValueSchema,
   'command.list': commandListValueSchema,
   'command.execute': commandExecuteValueSchema,
   'skill.list': skillListValueSchema,
@@ -400,6 +403,7 @@ export abstract class AbstractApiClient implements IApiClient {
     rename: (payload, signal) => this.callUnary('workspace.rename', payload, signal),
     delete: (payload, signal) => this.callUnary('workspace.delete', payload, signal),
     insertSessionBefore: (payload, signal) => this.callUnary('workspace.insertSessionBefore', payload, signal),
+    archiveSession: (payload, signal) => this.callUnary('workspace.archiveSession', payload, signal),
   }
 
   readonly commands: IApiClient['commands'] = {

packages/host/apiproxy/src/fetch/handler.ts

@@ -33,6 +33,7 @@ import {
   hostPickDirectoryRequestSchema,
 } from '../api/host.schema.ts'
 import {
+  workspaceArchiveSessionRequestSchema,
   workspaceCreateRequestSchema,
   workspaceDeleteRequestSchema,
   workspaceInsertSessionBeforeRequestSchema,
@@ -96,6 +97,7 @@ const UNARY_ROUTES: UnaryRoutes = {
   'workspace.rename': { schema: workspaceRenameRequestSchema, invoke: (api, r) => api.workspace.rename(r) },
   'workspace.delete': { schema: workspaceDeleteRequestSchema, invoke: (api, r) => api.workspace.delete(r) },
   'workspace.insertSessionBefore': { schema: workspaceInsertSessionBeforeRequestSchema, invoke: (api, r) => api.workspace.insertSessionBefore(r) },
+  'workspace.archiveSession': { schema: workspaceArchiveSessionRequestSchema, invoke: (api, r) => api.workspace.archiveSession(r) },
   'command.list': { schema: commandListRequestSchema, invoke: (api, r) => api.commands.list(r) },
   'command.execute': { schema: commandExecuteRequestSchema, invoke: (api, r, signal) => api.commands.execute(r, signal) },
   'skill.list': { schema: skillListRequestSchema, invoke: (api, r) => api.skills.list(r) },