Function format_bytes 

pub fn format_bytes(value: u64) -> String

What: Format bytes into human-readable string with appropriate unit.

Inputs:

• value: Number of bytes to format.

Output:

• Returns a formatted string like “1.5 MiB” or “1024 B”.

Details:

• Uses binary units (KiB, MiB, GiB, etc.) and shows integer for bytes < 1024, otherwise 1 decimal place.