- Studio.draw_auth_routes (default true) lets an app that already defines its
  own magic_link/solana routes (turf-monster) opt out of the engine drawing
  them, avoiding a duplicate route-name boot crash and keeping its routes intact.
- MagicLink re-exposes TOKEN_KEY + TTL constants (= config defaults) for
  back-compat with consumer code/tests; behavior still reads Studio config.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>