Markdown pictures: freed with their elements, glyphs whole, failures keep the source, file URLs parsed, Mermaid labels in Ely's ink

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

src/typography/mod.rs

@@ -25,6 +25,7 @@ pub use formatted::{
 };
 pub use inline::{Blockquote, Code, Highlight, Kbd, KbdCombo};
 pub use link::{ExternalLink, Link};
+pub(crate) use math::failed;
 pub use math::{Latex, MathError};
 pub use rolling::AnimatedNumber;
 pub use select::SelectableText;