Treat curly apostrophe as ASCII in spell check

Found while testing crates/engine/src/spell.rs:693 (paragraph_words) and :353 (Dictionary::check)

Co-Authored-By: Claude Haiku 5.5 <noreply@anthropic.com>
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

crates/engine/src/spell.rs

@@ -357,6 +357,9 @@ impl Dictionary {
 
     /// Is `word` spelt correctly? Capitalised and upper-case forms of a lower-case word pass.
     pub fn check(&self, word: &str) -> bool {
+        if word.contains('\u{2019}') {
+            return self.check(&word.replace('\u{2019}', "'"));
+        }
         if word.is_empty() || word.chars().all(|c| !c.is_alphabetic()) {
             return true;
         }
@@ -800,6 +803,13 @@ SFX D Y 1\nSFX D 0 ed/S .\n";
         Dictionary::parse(AFF.as_bytes(), DIC.as_bytes())
     }
 
+    #[test]
+    fn curly_apostrophe_matches_ascii_entry() {
+        let d = Dictionary::parse(AFF.as_bytes(), "2\ndon't\nwork\n".as_bytes());
+        assert!(d.check("don't"));
+        assert!(d.check("don\u{2019}t"));
+    }
+
     #[test]
     fn roots_affixes_and_cross_products_check() {
         let d = d();