EVENT_VIEWER_URL.replace(/\/$/, '') was duplicated across:
- env.ts (BRAND_LOGO, 1x)
- server.ts (settingsUrl in confirm routes, 3x)
- mailer.ts (settingsUrl in sendConfirm/sendDigest, 2x)
Now trailing-slash normalization happens at the export source in env.ts,
so all consumers get a clean URL without ad-hoc stripping.