fix(tests): lsp specs ride the seam scrub; acp e2e mounts the subprocess service

CI now exports DSH_GATE_CONCURRENCY into every job, and the lsp suites
spread the raw parent env into the spawn spec's ordinary channel — which
the seam rightly rejects for DSH_* names. The specs now build their child
env the way production does (scrubbedParentEnv() + explicit extras).
The acp with-key e2e never mounted dsh-subprocess-local, leaving the
provider's inject unsatisfied, so no 'acp' provider ever registered.

packages/subagent/subagent-acp/tests/subagent-acp.e2e.ts

@@ -6,6 +6,7 @@ import { afterEach, describe, expect, it } from 'vitest'
 import { Context } from 'cordis'
 import type { Agent } from '@deepseek-ai/dsh-agent'
 import SubagentService from '@deepseek-ai/dsh-subagent'
+import LocalSubprocessService from '@deepseek-ai/dsh-subprocess-local'
 import { resolveExampleLaunch } from '@deepseek-ai/dsh-loader-smoke'
 import * as acp from '../src/index.ts'
 
@@ -52,6 +53,7 @@ describe.skipIf(!process.env.DEEPSEEK_API_KEY)('ACP backend with-key e2e (drive
     workdir = await mkdtemp(join(tmpdir(), 'dsh-subagent-acp-e2e-'))
     ctx = new Context()
     await ctx.plugin(SubagentService)
+    await ctx.plugin(LocalSubprocessService)
     await ctx.plugin(acp, {
       providerName: 'acp',
       command: childLaunch.command,
@@ -81,6 +83,7 @@ describe.skipIf(!process.env.DEEPSEEK_API_KEY)('ACP backend with-key e2e (drive
     workdir = await mkdtemp(join(tmpdir(), 'dsh-subagent-acp-e2e-'))
     ctx = new Context()
     await ctx.plugin(SubagentService)
+    await ctx.plugin(LocalSubprocessService)
     await ctx.plugin(acp, {
       providerName: 'acp',
       command: childLaunch.command,