Function parse_duration 

pub fn parse_duration(s: &str) -> u64

Parse a human-readable duration string (e.g., “30d”, “2w”, “6M”) into seconds.

Supported suffixes:

• h — hours
• d — days
• w — weeks
• M — months (30 days)
• y — years (365 days)

If no suffix is provided, the value is treated as raw seconds. If parsing fails, returns 0.