Approve and, when eligible, synchronously materialize a proposal

Re-runs deterministic QA and synchronously materializes a human-approved proposal when detection and single-write are enabled. Human approval does not require the unattended auto-post flag. If single-write or detection is disabled, the row stays approved and the response reports approved_not_materialized. Re-approving resumes any partial write; posted rows are 200 no-ops. Other terminal rows return 409.