Add date and time handling, models, schedule management, storage, and widget support

- Introduced `Dates.swift` for handling date and time in the university's timezone.
- Created `Models.swift` to define data structures for timetable, lessons, and directory search results.
- Implemented `Schedule.swift` for managing lesson slots and timetable functionalities.
- Developed `Storage.swift` for user settings and data persistence.
- Added `Widgets.swift` to create widgets displaying lessons and upcoming classes.

.gitignore

@@ -3,3 +3,6 @@ dist/
 .data/
 *.tsbuildinfo
 .DS_Store
+xcuserdata/
+DerivedData/
+*.xcuserstate