fix(highlight): complete markdown syntax highlighting with injections

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

src/highlight.rs

@@ -25,9 +25,14 @@ const HIGHLIGHT_NAMES: &[&str] = &[
     "punctuation.delimiter",
     "punctuation.special",
     "string",
+    "string.escape",
     "string.special",
     "string.special.path",
     "string.special.uri",
+    "text.literal",
+    "text.reference",
+    "text.title",
+    "text.uri",
     "type",
     "type.builtin",
     "variable",
@@ -57,9 +62,14 @@ const HTML_ATTRS: &[&[u8]] = &[
     b" class=\"hl-punctuation-delimiter\"",
     b" class=\"hl-punctuation-special\"",
     b" class=\"hl-string\"",
+    b" class=\"hl-string-escape\"",
     b" class=\"hl-string-special\"",
     b" class=\"hl-string-special-path\"",
     b" class=\"hl-string-special-uri\"",
+    b" class=\"hl-text-literal\"",
+    b" class=\"hl-text-reference\"",
+    b" class=\"hl-text-title\"",
+    b" class=\"hl-text-uri\"",
     b" class=\"hl-type\"",
     b" class=\"hl-type-builtin\"",
     b" class=\"hl-variable\"",
@@ -189,7 +199,7 @@ static MARKDOWN_CONFIG: LazyLock<HighlightConfiguration> = LazyLock::new(|| {
     make_config(
         tree_sitter_md::LANGUAGE.into(),
         "markdown",
-        include_str!("../queries/md-highlights.scm"),
+        tree_sitter_md::HIGHLIGHT_QUERY_BLOCK,
         include_str!("../queries/md-injections.scm"),
     )
 });