fix: parse whole-second protobuf duration strings like 0s

[aadi-joshi]

Summary

Fix TimeDeltaSerializer._from_dict_value to accept protobuf JSON duration strings without a fractional component (e.g. 0s, 151s). The current implementation always splits on ., which crashes quota and other API responses that return whole-second durations.

Needs manual sync with the kapigen base.

Root cause

(seconds, nanosRaw) = value.rstrip("s").split(".")

Protobuf JSON allows whole-second values like 0s. When .split(".") returns one element, unpacking fails with ValueError: not enough values to unpack (expected 2, got 1).

Reported in Kaggle/kaggle-cli#1064.

Tests

Added TimeDeltaSerializerTests in kaggle_object_tests.py:

• whole-second durations (0s, 151s)
• fractional durations (151.500s) regression
• ApiGetAcceleratorQuotaStatisticsResponse JSON deserialization

Test plan

• TimeDeltaSerializer._from_dict_value("0s") returns timedelta(0)
• CI: python -m unittest kaggle_object_tests.TimeDeltaSerializerTests

[aadi-joshi]

Following up on stevemessick's guidance in Kaggle/kaggle-cli#1082. Marked for manual sync with the kapigen base. The auth portion of Kaggle/kaggle-cli#1064 is handled separately in #1082.