Add Zephyr support

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Coverage after merging zephyr-support into main will be

89.97%

Coverage Report

File	Stmts	Branches	Funcs	Lines	Uncovered Lines
src
action.c	84.31%	50%	100%	89.47%	21–22, 25, 28, 46–47, 50, 53
builtin_triggers.c	100%	100%	100%	100%
connection.c	68.42%	33.33%	100%	76.92%	10–11, 11, 11–12, 14, 16–17, 22, 5, 7, 7
environment.c	91.94%	100%	77.78%	93.88%	40, 45–46
port.c	95.56%	75%	100%	100%	14, 23
queues.c	89.31%	73.08%	100%	96.84%	100, 17, 31, 36, 39, 39, 39–40, 54–55, 71–75, 89, 94
reaction.c	91.04%	77.27%	100%	97.56%	26–27, 36, 38, 43, 7
reactor.c	74.55%	50%	100%	79.49%	11, 16–17, 17, 17–18, 20, 28, 31–32, 32, 32–33, 35
scheduler.c	94.74%	85%	100%	98.82%	100–101, 62, 78–80, 94
tag.c	33.68%	26.09%	40%	40.91%	21, 23, 26–27, 27, 27, 27, 27–28, 30, 30, 30, 30, 30–31, 33, 33, 33–34, 36–37, 37, 37–38, 40, 40, 40, 40, 40–41, 43, 43, 43, 43, 43–44, 46, 56–57, 59–60, 66, 70–71, 86–88, 88, 88, 88, 88, 88, 88, 88, 88, 88, 88–90, 92
timer.c	100%	100%	100%	100%
trigger.c	96.20%	81.25%	100%	100%	35, 40, 9
trigger_value.c	91.18%	62.50%	100%	100%	16, 18, 7
src/platform
posix.c	78.08%	42.86%	90.91%	85.42%	24, 29–30, 39, 41, 41, 41–42, 44, 54–56, 64, 70, 76