math in Persian text: lists read right-to-left, every content text goes through MathText, chat input picks its direction per line

Measured by rendering every question, option and several tutor answers in
Chrome and comparing the on-screen x of each number (2026-09-29):
- A list inside a sentence ('از −۳ به −۲، −۱، ۰ می‌رسیم', 'الگویِ ۲، ۵، ۸')
  was locked as one left-to-right run, so all 482 read backwards. '،' and
  '؛' outside brackets now split the run; sets and coordinates in brackets
  stay one run. Locked runs are isolates (isolate-override), otherwise the
  comma between two of them was still pulled left-to-right.
- Without MathText 704 of 931 minus signs and 602 of 983 expressions were
  misplaced; lesson and island titles, the lesson intro, unit blurb,
  notification bodies and ticket messages now go through it.
- The chat box takes its direction from each line's first letter, so a
  line of pure math stays left-to-right while typing. A line that starts
  in Persian can still show its math reordered inside the box; a textarea
  cannot isolate part of its text. The sent message renders correctly.

Four expressions with Persian words inside them ('f(x) = (ریشه دوم x) + ۵۰')
remain ambiguous.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/screens/LessonScreen.tsx

@@ -22,7 +22,7 @@ export function LessonScreen({ lessonId, nodeId }: { lessonId: number; nodeId?:
   return (
     <Screen>
       <ScreenHeader
-        title={data?.title ?? '…'}
+        title={data ? <MathText text={data.title} /> : '…'}
         color={color}
         back
         mascot={{ char: companion, mood: moodFromServer(data?.mascotAnimation), size: 72 }}
@@ -30,7 +30,7 @@ export function LessonScreen({ lessonId, nodeId }: { lessonId: number; nodeId?:
           ref && (
             <span className="inline-flex items-center gap-1.5 rounded-full bg-white/15 px-3 py-1">
               {/* ترتیبِ lessonIds «درسِ بعدی اول» است، نه ترتیبِ کتاب؛ پس شماره‌ی درس از آن درنمی‌آید. */}
-              <Zap size={11} fill="white" /> {ref.node.title}<Sep />{toFa(ref.node.lessonIds.length)} درس
+              <Zap size={11} fill="white" /> <MathText text={ref.node.title} /><Sep />{toFa(ref.node.lessonIds.length)} درس
             </span>
           )
         }
@@ -46,7 +46,7 @@ export function LessonScreen({ lessonId, nodeId }: { lessonId: number; nodeId?:
             <div className="flex items-start gap-3">
               <SeyarMascot char="sigma" mood="idle" size={56} />
               <div className="flex-1 rounded-3xl rounded-tr-sm border border-line bg-white p-4 shadow-sm">
-                <p className="whitespace-pre-line text-sm leading-[1.95] text-body">{data.introText}</p>
+                <p className="whitespace-pre-line text-sm leading-[1.95] text-body"><MathText text={data.introText} /></p>
               </div>
             </div>