typst: highlight function name after #set / #show keywords

KeywordExpr now optionally includes a CallExpr, so '#set text(size: 12pt)'
parses 'text' as a CallExpr/CodeIdent and gets the function-name highlight
colour.  The optional CallExpr only shifts when the lookahead is CodeIdent,
so there is no shift/reduce conflict with other items.

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

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

@@ -67,7 +67,10 @@ codeExprBody {
   ContentBlock
 }
 
-KeywordExpr { CodeKeyword }
+// CallExpr? covers '#set text(size: 12pt)', '#show heading: ...', etc.
+// The optional CallExpr is only shifted when the next token is CodeIdent,
+// so there is no shift/reduce conflict with other items that follow keywords.
+KeywordExpr { CodeKeyword CallExpr? }
 AtomExpr    { CodeBool    }
 
 CallExpr { CodeIdent callSuffix* }