Function slugify 

pub fn slugify(name: &str) -> String

Normalize a page name into a slug.

Rules:

• Lowercase
• Trim whitespace
• Split on / and normalize each segment independently
• Within each segment: replace spaces and underscores with hyphens, strip punctuation, collapse consecutive hyphens, trim leading/trailing hyphens
• Preserve Unicode alphanumeric characters
• Drop empty segments (handles //, leading /, trailing /)
• Rejoin with /