docs(api): better document zod schemas

[MathiasDevelopes]

While some of the variable names and the associated datatype is enough to make a good guess of what the variable actually contains, it is sub-optimal.

e.g

inskewl/src/api/types/timetable.ts

Line 16 in 03d690d

date: z.string(),

Date in this case is just a string. We dont know the format, unless there is documentation.

[MathiasDevelopes]

Actively being worked on, documenting code with Zod metadata and stricter / more correct types