Replace the W4d filename-based convention spec with a sweep of every
src/app/(campaign) file that calls mapCampaignFormActionError without
runCampaignFormAction/Redirect. Migrate profile, leaderSupporter, and
convite-login to the shared wrappers; allowlist auth/password and the
existing bespoke formActions exceptions with documented reasons.
Closes#241
Co-authored-by: Francisco Solla <fsolla@users.noreply.github.com>