feat(timezone): improve ux and time zone handling #566

Job	Run time
Clippy (stable)	23s
Clippy (Future) (beta)	23s
Build docs (stable, macos-latest)	26s
Clippy (Future) (nightly)	24s
Build docs (stable, ubuntu-latest)	1m 54s
Rustfmt	11s
Build docs (stable, windows-latest)	1m 14s
Check MSRV (pace-rs, 1.74.1)	2m 49s
ubuntu / stable / features	2m 25s
Check MSRV (pace_core, 1.74.1)	1m 53s
Test (stable, macos-latest)	7m 16s
Check MSRV (pace_cli, 1.74.1)	2m 2s
Test (stable, ubuntu-latest)	4m 53s
Test (stable, windows-latest)	9m 54s
Test (beta, macos-latest)	6m 8s
Test (beta, ubuntu-latest)	4m 58s
Test (beta, windows-latest)	9m 58s
Result (CI)	1s
	57m 12s

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