rebuild the app on a typed, modular structure wired to the real API

The whole app lived in one 3,071-line App.tsx on a Figma scaffold (60 unused
packages, 45 unused UI components, no type-check). The live site could not
reach the backend, Persian-keyboard digits were erased from the phone field,
guests were signed out after an hour, "mark read" hit a method the server
does not accept (405), and iOS Safari blocked the payment window.

What changed:
- src/ split into api/ (one typed client: timeouts, GET retry, single-flight
  refresh, SSE), screens/ (one file each), components/, state/, nav/, lib/.
- The API address is configuration only: public/config.js at runtime, then
  VITE_API_BASE_URL at build time, then same-origin /api. No domain in code.
- Responsive shell instead of a fixed 390x844 phone frame; self-hosted
  Vazirmatn instead of Google Fonts; strict TypeScript, `npm run build`
  type-checks first.
- Everything on the handoff list: tutor answers keep their line breaks, have
  thumbs up/down, follow-ups, "from the book" badge, retry, history that
  survives tab switches and reloads, "why was I wrong" from a wrong answer
  with questionId; question reports; hearts with maxHearts/unlimited and a
  no-hearts screen with the refill time; result screen and a visible error
  when lesson completion fails; subscription status, badge, discount code
  before the gateway and the payment-return message; guest refresh token;
  6-digit OTP with resend timer; age saved as a Jalali birthYear; PATCH
  read-all; leaderboard refetched on open with "you" highlighted; selected
  companion shown across the app; logout that revokes the refresh token.
- New screens for endpoints that had none: profile, streak calendar,
  support tickets and bug reports, parents, invite-a-friend (with ?ref=
  tracking), guest-to-phone upgrade.
- Browser/phone back button walks the screen stack.

Checked with a headless-Chrome walkthrough against a local backend at
390x844 and 360x740 (fresh guest: onboarding, setup, a full lesson, map,
island sheet, every tab and sub-screen, one real tutor question, reload,
logout): no console errors, no failed API calls. Real SMS login and a real
Zarinpal payment were not exercised.

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

.env.production

@@ -0,0 +1,8 @@
+# آدرسِ API در buildِ پروداکشن. تنها جایی از ریپو که دامنه‌ی بک‌اند نوشته شده.
+#
+# برای عوض کردنِ دامنه دو راه هست:
+#   ۱) همین خط را عوض کنید و دوباره build بگیرید.
+#   ۲) بدونِ build: روی سرور، در dist/config.js مقدارِ apiBaseUrl را بنویسید.
+#      آن فایل در زمانِ اجرا خوانده می‌شود و بر این مقدار مقدم است.
+# اگر nginxِ دامنه‌ی فرانت /api را به بک‌اند پراکسی کند، مقدارِ /api کافی است.
+VITE_API_BASE_URL=https://api.math.tadrisino2.ir/api