test: verify GitHub readiness on 2026-08-08

[ORESoftware]

Purpose

Non-production GitHub readiness proof for overnight engineering.

• creates no production state;
• contains one inert audit marker;
• exercises branch creation, contents write, PR creation, repository CI, and branch policy;
• must only merge if the exact head is green, conflict-free, and repository policy allows it.

Expected head: b0037d60dd66accdf70fede59ab7abaedfe359b6.

[linear-code]

DEN-3153