repair: revert accidental direct-main history

[justguy]

Why

• contains the feature payload through an accidental direct-main merge path
• protected branch settings require a PR-based linear history repair

What this does

• reverts so the follow-up overlay fix does not strand feature-only files during rollback
• reverts merge commit with parent as mainline
• returns the tree to the exact pre-merge baseline ()

Follow-up

• after this PR merges, merge PR feat: add runtime overlays and MCP patch tools #19 to put the verified code back onto through the normal protected PR flow