refactor(subprocess): the dispose ladder moves to its one consumer

SubprocessHandle loses dispose(graces) and SubprocessDisposeGraces: the
stdin-EOF→SIGTERM→SIGKILL sequence is teardown POLICY encoding one
consumer's cooperation shape, not process vocabulary — the seam keeps
kill/terminate/waitForExit, and waitForExit(signal?) is the quiescence
probe a consumer ladder needs. dsh-subagent-acp owns disposeAcpChild()
over those public verbs (tier tests move into its suite; a never-exits
stub pins the fail-loud path); dsh-subprocess-local sheds the ladder,
its deadline import, and the dsh-timeout dependency. Every future
backend now owes four verbs and no teardown policy. New bilingual
ladder-ownership Agent Note records the decision; catalogs regenerated.

packages/subprocess/subprocess/tests/service.spec.ts

@@ -1,7 +1,7 @@
 import { describe, expect, it } from 'vitest'
 import { Context } from 'cordis'
 import { scrubbedParentEnv, splitEnvChannels, SubprocessService } from '@deepseek-ai/dsh-subprocess'
-import type { SubprocessDisposeGraces, SubprocessHandle, SubprocessOutputRead, SubprocessSpawnSpec } from '@deepseek-ai/dsh-subprocess'
+import type { SubprocessHandle, SubprocessOutputRead, SubprocessSpawnSpec } from '@deepseek-ai/dsh-subprocess'
 
 /**
  * Minimal concrete service: a hand-built handle. The seam is spawn-only —
@@ -24,7 +24,6 @@ class StubSubprocessService extends SubprocessService {
       kill: () => {},
       terminate: () => {},
       waitForExit: () => Promise.resolve(true),
-      dispose: (_graces: SubprocessDisposeGraces) => Promise.resolve(),
     }
   }
 }
@@ -44,7 +43,6 @@ describe('SubprocessService seam', () => {
     handle.kill()
     handle.terminate()
     await expect(handle.waitForExit()).resolves.toBe(true)
-    await expect(handle.dispose({ eofGraceMs: 1, graceMs: 1 })).resolves.toBeUndefined()
     const outcome = await handle.done
     expect(outcome.exitCode).toBe(0)
   })