Fix markdown code block highlighting to properly support both markdown
structure (headings, frontmatter) and language injection (rust, bash).
The key fix uses `#set! injection.include-children` in the injection
query to override tree-sitter-md's internal tokenization, enabling
proper highlighting of embedded languages within code fences.
Changes:
- Use crate's HIGHLIGHT_QUERY_BLOCK for base markdown highlighting
- Add custom injection query with include-children directive
- Add YAML/TOML frontmatter and HTML block injection rules
- Add text.* highlight names (title, literal, uri, reference)
- Add string.escape highlight name
- Add CSS styles for new highlight classes
- Remove unused custom md-highlights.scm
Adapted Helix nix/injections.scm for tree-sitter-highlight:
- Removed Helix-specific predicates
- Recognizes bash in buildPhase/installPhase, python in testScript,
json in fromJSON, etc.
- queries/nix-highlights.scm: Adapted from Helix editor queries.
Properly identifies functions, properties, variable parameters,
escape sequences, and string interpolation. Much richer than
the bundled tree-sitter-nix query (99 lines vs 113 lines).
- src/highlight.rs: Load custom Nix query via include_str!
instead of using bundled HIGHLIGHTS_QUERY.
- static/style.css: Fix variable (#e36209) and punctuation (#586069)
colors to be distinct from text color.
Results: hl-function now appears (6 occurrences), hl-property
visible (17), hl-variable reduced from 43 to 17. Functions like
mkShell now render in purple/blue instead of orange.
