S00-012: Verify runner prompt delivery and lifecycle regressions

Changes: Record verification evidence and replace the blocked S00-012 handoff with independent QA review instructions. Retain the existing stdin implementation and regressions from prior checkpoints; no new source changes.
Validation: Reproduced the legacy partial stdin timeout on Python 3.9.6 and reaped the child. All 28 automation tests passed, including exact 140024-byte UTF-8/EOF and timeout/submit descendant cleanup. make check passed all 72 tests; git diff --check passed. No live model, application readiness or Windows cleanup check is claimed.

Task: S00-012
Agent: auto-ci-cd-f101e40d9902
Role: ci-cd
Action: claim
Status: review

Task title: Fix runner prompt delivery after partial stdin timeout

planning/stages/S00.md

@@ -16,7 +16,7 @@
 - [S00-008](../tasks/S00-008.md): Описать WSS/upload/TURN/push topology — ci-cd; todo.
 - [S00-009](../tasks/S00-009.md): Согласовать результаты spikes — orchestrator; todo.
 - [S00-011](../tasks/S00-011.md): Restore verified npm registry access for the stack spike — ci-cd; done.
-- [S00-012](../tasks/S00-012.md): Fix runner prompt delivery after partial stdin timeout — ci-cd; todo.
+- [S00-012](../tasks/S00-012.md): Fix runner prompt delivery after partial stdin timeout — ci-cd; review.
 - [S00-013](../tasks/S00-013.md): Bound oversized S21-006 runner context without truncating requirements — ci-cd; done.
 - [S00-014](../tasks/S00-014.md): Fix repeated runner cleanup after a submitted parent is reaped — ci-cd; done.
 - [S00-010](../tasks/S00-010.md): Gate: Профиль и проверка стека — qa; todo.