- Add monospace_attrs() function in main.rs to centralize monospace font attributes creation
- Replace duplicated Attrs::new().family(Family::Monospace) calls in:
* line_number.rs: LineNumberCache::get() method
* main.rs: App::init() font enumeration
* tab.rs: EditorTab::new() constructor
- Remove unused imports (Attrs, Family) from line_number.rs
- Resolves TODO comments about code repetition across modules
This change improves maintainability by having a single source of truth
for monospace font configuration.
