Add arithmetic support (add/subtract) to the Time type

[Binilkks]

Feature Request: Time.add() / Time.subtract() arithmetic

Problem

Every major type in whenever supports arithmetic via add() and subtract() — Date, Instant, ZonedDateTime, OffsetDateTime, PlainDateTime — but Time does not.

This makes it awkward to work with time-of-day arithmetic, which is common in scheduling scenarios (store hours, shift times, reminders, etc.).

Expected Behavior

Time(22, 0).add(hours(3))      # → Time(1, 0), wraps past midnight
Time(1, 0).subtract(hours(3))  # → Time(22, 0), wraps before midnight

Arithmetic could wrap around midnight (modular arithmetic), consistent with how most users would expect time-of-day math to work.

Current Workaround

Users currently have to manually handle the math via _to_ns_since_midnight() internals or convert to PlainDateTime first, which is verbose and leaks implementation details.

Suggested Signature

def add(self, delta: TimeDelta, /) -> Time: ...
def subtract(self, delta: TimeDelta, /) -> Time: ...

Operator overloads (__add__, __sub__) could also follow the same pattern as other types.

Notes

Python's stdlib datetime.time also skips arithmetic, so this would be a meaningful improvement over the standard library behavior.

[ariebovenberg]

Thanks for taking the time to submit this issue. This feature looks sensible 👍 . The only issue is whether the wraparound behaviour should require setting a wraparound=True kwarg. I'm thinking there are cases in which this might not be the intended behavior. Perhaps even a more flexible overflow='wrap'|'raise'|'cap' or similar, since caping the times might also be desirable in some cases.