Spike: Decide fate of RailsRelease#github_actions_sanity_check! (remove vs complete wiring)

[JuanVqz]

RailsRelease#github_actions_sanity_check! in app/models/rails_release.rb appears to be dead code today.

Context:

• Introduced in commit f46f42b (2024-10-07, “Add sanity check method”) with intent to dispatch a workflow in railsbump/checker.
• Method and related constants/inputs are not referenced elsewhere in this codebase.
• There is existing GitHub Actions wiring in Compats::Checks::BundlerGithubCheck, so this model-level path may be unfinished or superseded.
• Including @etagwerker for historical context, since he authored the introducing commit.

Decision needed:

• Option A: remove github_actions_sanity_check! and related constants/private helper.
• Option B: finish wiring and define where/how this method is called, error handling, required env vars, and expected workflow contract.

Acceptance criteria:

• Team chooses A or B.
• If A: remove method/constants/helper plus tests/docs updates.
• If B: implement end-to-end call path plus tests and operational docs (GITHUB_ACCESS_TOKEN, workflow inputs/outputs, failure behavior).

[JuanVqz]

Investigated and this is dead code #170