Function parse_rfc3339_with_timezone 

pub fn parse_rfc3339_with_timezone(
    s: &str,
) -> Result<DateTime<FixedOffset>, ProjectionError>

Parse RFC3339 timestamp with strict timezone validation.

Kept for callers that explicitly require timezone-bearing input. Prefer parse_timestamp_flexible for user-facing inputs (CSV/GeoJSON files, detection feeds, etc.) where a naive datetime should be accepted.