fix(ci): follow repaired Feature Stack PRs

[lopugit]

What changed

• pin Feature Stack completion to the published PR number and exact head/base branch identity
• keep following that protected PR when an authorized repair push advances its head
• add a controller contract preventing stale exact-SHA matching from returning
• refresh the bounded Graphify snapshot and control-plane changelog

Why

Feature Stack run f2023eb8-a7a5-4903-ba83-65a73c02dc4f published PR #566, then an authorized CI repair advanced the same PR head. GitHub merged #566 with all required checks green, but the wrapper had captured the original head SHA and could never observe the merge.

Validation

• node .github/scripts/workflow-control-plane-contract.mjs --self-test
• live lookup pins PR Feature Stack: Lopu auto stack merge test 1 -> main #566 by exact branch/base and reads its merged timestamp
• git diff --check

The broader resolver routing self-test still has its pre-existing baseline failure expecting the retired anthropic-api-key-fallback input; this change does not touch that contract.