fix(typst): exclude ] from MarkupContent so ContentBlock always closes

The core bug: MarkupContent { ![...]+ } did not exclude ']', so inside
#figure(table([A],[B]), caption:[...]) the tokenizer consumed ']' as
MarkupContent, ContentBlocks never closed, and all remaining args like
'caption:' were swallowed as MarkupContent instead of CodeArgKey.

Fix mirrors the LaTeX grammar pattern (its Normal token excludes \] and
\[): add ']' to MarkupContent's exclusion set and provide ClosingSquare
{ "]" } as an item alternative for bare ']' in body text.  The grammar's
existing @precedence { "]" ClosingSquare } ensures "]" wins and closes
the ContentBlock; outside a ContentBlock only ClosingSquare is valid.

Also change URL style tag from t.url (tok-url, unstyled in all themes)
to t.string (tok-string, styled in every theme).

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

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

@@ -78,7 +78,7 @@ export const TypstLanguage = LRLanguage.define({
         'Emphasis/"_" Emphasis/EmphBody': t.emphasis,
 
         // Bare URLs (https://... / http://...)
-        URL: t.url,
+        URL: t.string,
 
         // Labels (<name>) and references (@name)
         'Label/"<" Label/">" Label/LabelName': t.labelName,

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

@@ -28,7 +28,8 @@ item {
   Ref |
   Escape |
   URL |
-  MarkupContent
+  MarkupContent |
+  ClosingSquare
 }
 
 // ── Headings ──────────────────────────────────────────────────────────────
@@ -226,8 +227,14 @@ Escape { "\\" EscapeChar }
 
   // 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.
+  // '/*' are not accidentally consumed as plain text.  ']' is excluded so
-  MarkupContent { ![\n \t=*_$#/<@`\\]+ }
+  // that ContentBlock { "[" item* "]" } can always close reliably — a bare
+  // ']' in body text is matched as ClosingSquare instead.
+  MarkupContent { ![\n \t\]=*_$#/<@`\\]+ }
+
+  // Fallback for a bare ']' in markup text (outside any ContentBlock).
+  // Inside ContentBlock the literal "]" terminal wins via @precedence.
+  ClosingSquare { "]" }
 
   // Label names: identifiers with optional dots/colons (e.g. <sec:intro>).
   LabelName { (@asciiLetter | "_" | @digit) (@asciiLetter | @digit | "_" | "-" | "." | ":")* }
@@ -248,7 +255,7 @@ Escape { "\\" EscapeChar }
   // CodeString > MarkupContent: '"' starts a string literal after a keyword.
   // ":"  > MarkupContent: keywordBody ':' wins over markup colon in code states.
   // URL > MarkupContent: 'https://' / 'http://' wins over plain markup text.
-  @precedence { CodeBool EscapeChar CodeString URL "[" ":" "(" "." "]" "_" spaces MarkupContent }
+  @precedence { CodeBool EscapeChar CodeString URL "[" ":" "(" "." "]" ClosingSquare "_" spaces MarkupContent }
 }
 
 @skip { spaces }