Submit Pull Request Review: Footer rendering bug

[strawgate]

After merging the latest footer PR (to add if-body) copilot noticed a bug after merge (the worst time to notice a bug): #15643 (review)

Copilot missed implementing the final part of the ask True/false map to always/none

SubmitPullRequestReviewConfig.Footer is typed as *bool in Go, so the Go compiler emits a boolean value (e.g., "footer": false) in the JSON config for submit_pull_request_review. However, after PR #15643, setFooterMode() in JavaScript only accepts strings ("always", "none", "if-body"). When the fallback path reads submit_pull_request_review.footer (a boolean), it passes it to setFooterMode(), which rejects it as an invalid type and silently resets to "always" -- the opposite of the user's intent.