Function format_unix_timestamp 

pub fn format_unix_timestamp(unix_timestamp: i64, pattern: &str) -> String

Formats a Unix timestamp using Python-like strftime tokens.

Supported tokens:

• %Y year with century (e.g. 2026)
• %m month as zero-padded decimal (01..12)
• %d day of month as zero-padded decimal (01..31)
• %H hour (24-hour clock) as zero-padded decimal (00..23)
• %I hour (12-hour clock) as zero-padded decimal (01..12)
• %M minute as zero-padded decimal (00..59)
• %S second as zero-padded decimal (00..59)
• %p locale-independent AM/PM
• %% literal %