Add migration 0018 with unique indexes on recipe_ingredients and
recipe_steps (recipe_id, position), so a recipe can never hold two
ingredients or two steps at one position. The dinner detail read now
orders by position alone and drops its read-time duplicate check; a
database already holding a duplicate fails the migration.
Maestro task 75bb8cc1-fd30-4050-90d2-a1627a865b22
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
