refactor to extract ntp update logic

[mMerlin]

Extract the ntp lookup logic to a separate method. change to use integer nanoseconds for the monotonic start reference.

• this provides sub-second accuracy. For the datetime property, that adjusts exactly when the seconds value rolls over to the next second.

Add utc_ns property to return the raw nanoseconds since the unix epoch. For cases were more precision than ±1 second is wanted.

[mMerlin]

It seems that black does not like where I did or did not wrap lines. Should I edit to match and re-push?

[mMerlin]

setup local precommit to adjust formatting. updated 2 of the examples to use settings.toml instead of secrets.py.