- src/highlight.rs: Add 7 new captures to HIGHLIGHT_NAMES:
embedded, escape, function, punctuation.special, string.special,
string.special.path, string.special.uri. Now 27 total captures.
- static/style.css: Add CSS variables and class rules for new
captures in both light and dark themes. escape gets bold
styling, string-special uses distinct color.
These captures are used by tree-sitter-nix but were previously
missing, causing sparse highlighting. Now functions, escapes,
and paths are properly highlighted.