fix(prt): fix fpe by constraining local z coord to unit interval #3882

Job	Run time
Build	1m 58s
Smoke test	5m 52s
Check format	1m 14s
Extended testing (ubuntu-22.04)	18m 38s
Test Intel fortran (ubuntu-22.04)	39m 5s
Test GNU fortran (macos-13, false)	43m 20s
Test Intel fortran (macos-13)	36m 23s
Extended testing (macos-13)	48m 11s
Test GNU fortran (macos-14, false)	30m 3s
Test Intel fortran (windows-2022)	33m 35s
Extended testing (windows-2022)	47m 50s
Test GNU fortran (macos-14, true)	1h 0m 38s
Test GNU fortran (ubuntu-22.04, false)	38m 33s
Test GNU fortran (ubuntu-22.04, true)	1h 30m 22s
Test GNU fortran (windows-2022, false)	48m 42s
	9h 4m 24s

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