feat(subprocess): migrate lsp-local, subagent-acp, and the env scrubs onto the seam

Review direction (tianyicui, PR #660): in a stacked PR, change all other
process-running places to use the new service.

- lsp-local: LspConnection spawns through ctx.subprocess (piped protocol
  streams + a no-spill collected stderr tail); its private process-tree
  helpers (POSIX group signalling, Windows taskkill, liveness polling) are
  deleted in favor of the seam's handle verbs, and its buildChildEnv now
  rides scrubbedParentEnv (LSP children also stop inheriting stale DSH_*).
  The plugin injects 'subprocess'; compositions/tests mount
  dsh-subprocess-local.
- subagent-acp: the ACP child spawns through the seam (piped ndjson streams,
  inherited stderr); spawn failure surfaces through done-rejection into the
  same startup race; disposal is handle.dispose with the plugin's configured
  graces. dsh-subagent-subprocess is DELETED — its dispose ladder and scrub
  are the seam's, and the isolated-config-dir helper had no consumer.
- mcp-client, pty-local, sdk-helper: adopt scrubbedParentEnv as the one
  scrub definition (their spawns stay put by ownership: the MCP SDK and
  node-pty own those calls; the SDK wizard runs outside any composition).
- Coverage: per-file 100% over every touched src file, with each v8 ignore
  carrying a platform or contract reason; new suites cover stdio
  dispositions, the dispose ladder tiers, injected-win32 tree semantics,
  waitForExit, settled-kill/terminate no-ops, and spawn-failure disposal.
- Docs: consumer-migration Agent Note (en; zh follows in this PR), seam note
  updated in place, subprocess.md rewritten for the reshaped vocabulary
  (type-equiv re-registered), READMEs and SERVICE_ROLES updated, taskkill
  added to knip ignoreBinaries.

docs/cordis-catalog/services.md

@@ -1565,24 +1565,24 @@ Abstract subprocess service. Subclass, implement spawn, and load the subclass as
 
 Implementations must honor these semantics:
 
-- spawn returns immediately with a live handle; `done` resolves at process close and rejects only for spawn-level failures.
-- Output readers are offset-based and non-consuming, so independent readers never consume one another's output; lossy reads report truncation and the spill file holding the complete stream when one exists.
-- SubprocessHandle.kill and the spec's abort signal escalate SIGTERM→grace→SIGKILL across the whole process group.
-- Disposal kills all still-running managed processes and awaits their exit.
+- spawn returns immediately with a live handle; `done` resolves at process close with exit facts and rejects only for spawn-level failures.
+- Collect-mode readers are offset-based and non-consuming, so independent readers never consume one another's output; lossy reads report truncation and the spill file holding the complete stream when one exists. Piped streams are handed to the caller raw and never buffered here.
+- SubprocessHandle.kill signals without escalation, SubprocessHandle.terminate (and the spec's abort signal) escalates SIGTERM→grace→SIGKILL, and SubprocessHandle.dispose runs the cooperative EOF-first ladder — all tree-scoped on every platform.
+- Disposal of the service terminates all still-running managed processes and awaits their exit.
 
 ```ts cordis-catalog
 /**
  * Start one managed child process from a fully-specified spec; this seam
  * applies no defaults.
- * @param spec - argv, directory, limits, grace, cancellation, and environment.
- * @returns the live process handle (readers, kill, outcome promise).
+ * @param spec - argv, directory, stdio dispositions, grace, cancellation, and environment.
+ * @returns the live process handle (streams/readers, signalling, outcome promise).
  */
 abstract spawn(spec: SubprocessSpawnSpec): SubprocessHandle
 ```
 
 Types: [SubprocessHandle](../core-data-structures/subprocess.md) · [SubprocessSpawnSpec](../core-data-structures/subprocess.md)
 
-Source: [`packages/subprocess/subprocess/src/index.ts:48`](../../packages/subprocess/subprocess/src/index.ts)
+Source: [`packages/subprocess/subprocess/src/index.ts:90`](../../packages/subprocess/subprocess/src/index.ts)
 
 ## `ctx.systemPrompt` — `SystemPrompt`