Fix 29 audit findings across all severity tiers

src/i18n.rs

@@ -23,7 +23,6 @@ pub fn i18n_f(msgid: &str, args: &[(&str, &str)]) -> String {
 }
 
 /// Translate a string with singular/plural forms and named placeholders.
-#[allow(dead_code)]
 pub fn ni18n_f(singular: &str, plural: &str, n: u32, args: &[(&str, &str)]) -> String {
     let base = if n == 1 { singular } else { plural };
     let mut result = base.to_string();