Function format_bordered_box 

pub fn format_bordered_box(lines: &[&str], color: bool) -> String

Format text inside a bordered box using box-drawing characters.

┌────────────────────────────────────────┐
│ your content here                      │
│ second line                            │
└────────────────────────────────────────┘

Used for code/config snippet display (e.g., future seshat init output).