typst: fix URL comment split and heading label highlighting

- Add URL token (https://... / http://...) so '://' is never split into
  ':' + LineComment '//', preventing URLs from being styled as comments
- Stop headingTitleTokenizer before '<label>' patterns so labels at the
  end of headings get Label node styling instead of being consumed as
  heading title text
- Style URL nodes with t.url tag

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

services/web/frontend/js/features/source-editor/languages/typst/index.ts

@@ -77,6 +77,9 @@ export const TypstLanguage = LRLanguage.define({
         'Strong/"*" Strong/StrongBody': t.strong,
         'Emphasis/"_" Emphasis/EmphBody': t.emphasis,
 
+        // Bare URLs (https://... / http://...)
+        URL: t.url,
+
         // Labels (<name>) and references (@name)
         'Label/"<" Label/">" Label/LabelName': t.labelName,
         'Ref/"@" Ref/RefName': t.labelName,

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

@@ -35,6 +35,8 @@ const DOT         = 46  // .
 const OPEN_PAREN  = 40  // (
 const COMMA       = 44  // ,
 const COLON       = 58  // :
+const OPEN_ANGLE  = 60  // <
+const CLOSE_ANGLE = 62  // >
 
 const KEYWORDS = new Set([
   'let', 'set', 'show', 'import', 'include',
@@ -87,6 +89,17 @@ export const headingTitleTokenizer = new ExternalTokenizer(
     while (input.next !== -1 && input.next !== NEWLINE) {
       if (input.next === SLASH &&
           (input.peek(1) === SLASH || input.peek(1) === STAR)) break
+      // Stop before a trailing '<label>' so it is parsed as a Label node
+      // rather than being merged into the heading title text.
+      // Only stops when '<' is immediately followed by a valid label name and '>'.
+      if (input.next === OPEN_ANGLE) {
+        const ch = input.peek(1)
+        if (isAlpha(ch) || isDigit(ch) || ch === UNDERSCORE) {
+          let j = 2
+          while (isIdentTail(input.peek(j)) || input.peek(j) === DOT || input.peek(j) === COLON) j++
+          if (input.peek(j) === CLOSE_ANGLE) break
+        }
+      }
       input.advance()
       hasContent = true
     }

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

@@ -27,6 +27,7 @@ item {
   Label |
   Ref |
   Escape |
+  URL |
   MarkupContent
 }
 
@@ -218,6 +219,11 @@ Escape { "\\" EscapeChar }
     ("pt" | "mm" | "cm" | "in" | "em" | "rem" | "fr" | "deg" | "rad" | "%")?
   }
 
+  // URL: bare https:// or http:// links in markup text.  Matched as a single
+  // token so '://' is never split into ':' + LineComment '//…'.  Stops at
+  // whitespace and angle brackets (labels use '<…>').
+  URL { ("https" | "http") "://" (![ \t\n<>])* }
+
   // Regular markup: excludes all special-character starters plus whitespace
   // (whitespace is handled by @skip).  The '/' is excluded so that '//' and
   // '/*' are not accidentally consumed as plain text.
@@ -241,7 +247,8 @@ Escape { "\\" EscapeChar }
   // "["  > MarkupContent: ContentBlock callSuffix wins in merged code/markup states.
   // CodeString > MarkupContent: '"' starts a string literal after a keyword.
   // ":"  > MarkupContent: keywordBody ':' wins over markup colon in code states.
-  @precedence { CodeBool EscapeChar CodeString "[" ":" "(" "." "]" "_" spaces MarkupContent }
+  // URL > MarkupContent: 'https://' / 'http://' wins over plain markup text.
+  @precedence { CodeBool EscapeChar CodeString URL "[" ":" "(" "." "]" "_" spaces MarkupContent }
 }
 
 @skip { spaces }