Refactor scheduling.vue state to colocate providers with their time slots
Replace parallel inShopProviders/inshopTimeSlots arrays with a single
inShopProvidersAndTimeslots array of { provider, timeSlots } objects, and
combine mobileTimeSlots/mobileProviderNumber into a single
mobileProviderAndTimeSlot object. Also extract SCHEDULE_FETCH_DAYS constant
to replace the magic number 14
add JSDoc to toDateString, and remove the
unused inShopProviderNumber state.