Regex pattern for Temporal.Instant ISO 8601 strings
(e.g. 2023-01-15T13:45:30Z or 2023-01-15T13:45:30+05:30).
Validates month (01–12), day (01–31), hours (00–23), minutes/seconds (00–59),
up to 9 fractional digits, and a required UTC offset (Z or ±HH:MM).
An optional IANA timezone annotation in brackets is permitted.
Regex pattern for Temporal.Instant ISO 8601 strings (e.g.
2023-01-15T13:45:30Zor2023-01-15T13:45:30+05:30). Validates month (01–12), day (01–31), hours (00–23), minutes/seconds (00–59), up to 9 fractional digits, and a required UTC offset (Z or ±HH:MM). An optional IANA timezone annotation in brackets is permitted.