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.