refactor: command.execute degrades to pure admission; composer notice channel retired

The wire response now carries only the matched bit — CommandExecuteResult
is deleted from the api, schema, and client mirrors (pre-release, no shim);
outcomes ride the durably logged command/run/command/done pair broadcast on
the mux stream and render as flow nodes. ui-command's runDetached→noticeFor
outcome routing is retired: admitted commands surface nothing through the
composer, while admission misses (matched:false, syntax feedback) and
transport failures keep their immediate notice. The connection fixture
mirrors the host: an admitted command appends the lifecycle pair to the
session log instead of returning result text.

packages/host/apiproxy/src/api/commands.schema.ts

@@ -7,7 +7,7 @@ import { z } from 'zod'
 import type { RequestPayload, ResponseValue } from './rpc-map.ts'
 import type { Wire } from './rpc.schema.ts'
 import { sessionIdSchema } from './sessions.schema.ts'
-import type { CommandDescriptor, CommandExecuteResult } from './commands.ts'
+import type { CommandDescriptor } from './commands.ts'
 
 /** CommandDescriptor row of command.list. */
 export const commandDescriptorSchema = z.object({
@@ -32,14 +32,7 @@ export const commandExecuteRequestSchema = z.object({
   line: z.string(),
 }) satisfies z.ZodType<Wire<RequestPayload<'command.execute'>>>
 
-/** Detached command outcome (result slot of command.execute's value). */
-export const commandExecuteResultSchema = z.object({
-  kind: z.union([z.literal('success'), z.literal('error')]),
-  text: z.string().optional(),
-}) satisfies z.ZodType<Wire<CommandExecuteResult>>
-
-/** command.execute response value (matched=false carries no result). */
+/** command.execute response value: pure admission — outcomes ride the logged lifecycle events, never this response. */
 export const commandExecuteValueSchema = z.object({
   matched: z.boolean(),
-  result: commandExecuteResultSchema.optional(),
 }) satisfies z.ZodType<Wire<ResponseValue<'command.execute'>>>