Exercises and workouts both have a favorite toggle; yoga poses had an
otherwise identical browse/filter UX but no way to favorite them - an
inconsistency rather than a deliberate omission. Mirrors the existing
exercise/workout favorite pattern exactly: a pivot table, a
belongsToMany on User, and a toggle button on the pose detail page.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>