Draw only the first character of a multi-character bullet

PowerPoint draws buChar char="••" (seen in a LibreOffice test deck) as a
single dot; DeckCraft drew both, pushing the text right.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

crates/text/src/lib.rs

@@ -679,7 +679,8 @@ fn map_symbol_bullet(c: &str, font: Option<&str>) -> String {
         };
         return m.to_string();
     }
-    c.to_string()
+    // PowerPoint draws only the first character of a longer `buChar` ("••" draws one dot).
+    c.graphemes(true).next().unwrap_or("•").to_string()
 }
 
 fn measure_str(face: &FontFace, size: f64, s: &str) -> (f64, Vec<(u32, f64)>) {

crates/text/src/tests.rs

@@ -45,6 +45,20 @@ fn bullets_are_drawn_for_body_text() {
     assert_eq!(l.para_lines.len(), 2);
 }
 
+#[test]
+fn only_the_first_character_of_a_bullet_is_drawn() {
+    // "••" (seen in the wild) draws one dot in PowerPoint.
+    for (char, glyphs) in [("\u{2022}\u{2022}", 1), ("\u{2022}", 1), ("-->", 1)] {
+        let (p, mut sh) = setup("One", 600.0, 300.0);
+        sh.text.as_mut().unwrap().paragraphs[0].props.bullet = Some(Bullet::Char { char: char.into() });
+        let l = lay(&p, &sh, 600.0, 300.0);
+        let bullet = l.runs.iter().find(|r| r.chars == (0, 0)).expect("bullet run");
+        assert_eq!(bullet.glyphs.len(), glyphs, "{char:?}");
+    }
+    // The first grapheme cluster is kept whole.
+    assert_eq!(map_symbol_bullet("e\u{301}x", None), "e\u{301}");
+}
+
 #[test]
 fn shrink_on_overflow() {
     let text = (0..30).map(|i| format!("Line number {i}")).collect::<Vec<_>>().join("\n");