Function format_uptime 

pub fn format_uptime(seconds: u64) -> String

Format an uptime in seconds as "Xd Yh Zm" (or shorter when leading units are zero).

Examples:

• 0 → "0m"
• 59 → "0m"
• 3600 → "1h"
• 3660 → "1h 1m"
• 86400 → "1d"
• 90061 → "1d 1h 1m"