refactor(subprocess): rename the process seam to subprocess and address review

Review feedback (tianyicui): 'process' is a poor service name. The family is
now packages/subprocess/ — @deepseek-ai/dsh-subprocess (ctx.subprocess,
abstract SubprocessService, Subprocess* vocabulary) and
@deepseek-ai/dsh-subprocess-local (LocalSubprocessService) — renamed
throughout code, compositions, docs (en+zh, pairs re-recorded), catalogs,
and gates. 'subprocess' is the precise term for managed OS children (the
Python-stdlib sense), avoids colliding with Node's global process object,
and reads as one system beside dsh-subagent-subprocess.

ds-review-bot findings addressed:
- kill() on a settled handle is now a no-op (no signal to a possibly-reused
  pgid, no referenced grace timer delaying exit); pinned by a spy test.
- The moved DshEnvironmentKey/DshEnvironment/CollectedOutput types get
  drift-checked type-equiv blocks on the new subprocess.md page, restoring
  their manifest registration.
- subprocess.md is registered in the core.md sub-page index (en+zh).

packages/bash/bash/src/index.ts

@@ -44,8 +44,8 @@ declare module 'cordis' {
  * - {@link BashProcess.readOutput} is incremental: consecutive reads never
  *   repeat output. Lossy reads report truncation and available spill files.
  * - A still-running background process is stopped and awaited when its
- *   owning composition tears down. With the process-manager seam that
- *   boundary is `ctx.processes` disposal, so a background process survives
+ *   owning composition tears down. With the subprocess seam that
+ *   boundary is `ctx.subprocess` disposal, so a background process survives
  *   an executor-only reload.
  */
 export abstract class BashExecutor extends Service {

packages/bash/bash/src/types.ts

@@ -2,16 +2,16 @@
  * Execution types for the bash executor seam. Background task semantics belong
  * to `@deepseek-ai/dsh-tasks`; this seam exposes only process handles. The
  * managed-environment and captured-output vocabulary is owned by the
- * process-manager seam and re-exported here so bash consumers keep one import
+ * subprocess seam and re-exported here so bash consumers keep one import
  * root.
  * @module dsh-bash/types
  */
 
 import type { SandboxEnforcement, SandboxExecutionPolicy, SandboxMode } from '@deepseek-ai/dsh-sandbox'
-import type { CollectedOutput, DshEnvironment } from '@deepseek-ai/dsh-process'
+import type { CollectedOutput, DshEnvironment } from '@deepseek-ai/dsh-subprocess'
 
-export { DSH_ENV_PREFIX } from '@deepseek-ai/dsh-process'
-export type { CollectedOutput, DshEnvironment, DshEnvironmentKey } from '@deepseek-ai/dsh-process'
+export { DSH_ENV_PREFIX } from '@deepseek-ai/dsh-subprocess'
+export type { CollectedOutput, DshEnvironment, DshEnvironmentKey } from '@deepseek-ai/dsh-subprocess'
 
 /**
  * Sandbox facts for one run, present iff a sandboxing executor handled it.
@@ -154,7 +154,7 @@ export interface BashProcessRead {
 /**
  * A background process handle returned by {@link BashExecutor.start}. It is the
  * only access path; buffered output remains readable after exit. Composition
- * teardown (the process manager's disposal) kills running processes and
+ * teardown (the subprocess service's disposal) kills running processes and
  * awaits {@link done}; an executor-only reload leaves them running.
  */
 export interface BashProcess {