fix(typst): highlight idents after #keyword and wire tok-attributeName

- codeIdentTokenizer: extend guard to scan back through the keyword word
  and accept when '#' immediately precedes it, so 'text' in '#set text(...)'
  and 'heading' in '#show heading:' are highlighted as function names
- classHighlighter: add tags.attributeName → tok-attributeName mapping;
  all 26 themes already define .tok-attributeName colours but the tag was
  never mapped to the class, leaving named arg keys (columns:, caption:)
  completely unstyled

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

services/web/frontend/js/features/source-editor/extensions/class-highlighter.ts

@@ -46,5 +46,6 @@ export const classHighlighter = tagHighlighter([
   { tag: tags.invalid, class: 'tok-invalid' },
   { tag: tags.punctuation, class: 'tok-punctuation' },
   // additional
+  { tag: tags.attributeName, class: 'tok-attributeName' },
   { tag: tags.attributeValue, class: 'tok-attributeValue' },
 ])

services/web/frontend/js/features/source-editor/lezer-typst/tokens.mjs

@@ -321,12 +321,17 @@ export const codeIdentTokenizer = new ExternalTokenizer(
     if (!stack.canShift(CodeIdent)) return
 
     // Guard: only fire in code context.
-    // Walk back past whitespace (including newlines inside multi-line arg lists)
+    // Walk back past whitespace to the nearest non-space character.
-    // to the nearest non-space character and check that it is a code-mode delimiter.
     let back = -1
     while (input.peek(back) === SPACE || input.peek(back) === TAB || input.peek(back) === NEWLINE) back--
     const prev = input.peek(back)
-    if (prev !== HASH && prev !== DOT && prev !== OPEN_PAREN && prev !== COMMA) return
+    if (prev !== HASH && prev !== DOT && prev !== OPEN_PAREN && prev !== COMMA) {
+      // May be after a keyword like '#set' or '#show': scan back through the
+      // keyword word itself and check that '#' immediately precedes it.
+      if (!isIdentTail(prev)) return
+      while (isIdentTail(input.peek(back))) back--
+      if (input.peek(back) !== HASH) return
+    }
 
     // Must start with an identifier head character.
     if (!isIdentHead(input.next)) return