The selected companion everywhere, each with a small trait; next-APK notes

- state/companion.ts: one store for the chosen companion (also in localStorage so splash/login show it).
  BrandMark (the orange «π» tile) now shows the companion's symbol (Σ Δ π ω) in its colour; screen-header
  mascots, loaders and empty/error states default to it; the assistant is «از {name} بپرس» with its face,
  colour and wording; the shop, lesson and quiz «ask» buttons name it; the active tab takes its tint.
- Traits, all client-side and light: Σ sigma keeps a running tally of correct answers in the quiz header;
  Δ delta shows a flame «×N» chip and an extra buzz for answers in a row; π pi gives a short solving tip
  after a wrong answer; ω omega throws gold confetti at the end of every island whatever the score.
  Each companion's «correct» sound is pitched differently; confetti uses its colours. Characters screen
  lists each trait.
- android/README.md: what MainActivity.kt has that the installed APK lacks (vibrate bridge, media gesture,
  in-app gateway + paysInApp), what to check on a phone after building, signing owner, Bazaar policy note.

Checked in headless Chrome with Sigma, Delta and Omega selected (home, assistant, shop, characters, quiz).

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

src/screens/ReportScreen.tsx

@@ -7,6 +7,7 @@ import { SeyarMascot } from '@/mascots/SeyarMascot';
 import type { SeyarMood } from '@/mascots/seyar';
 import { ErrorState, LoadingState, Screen, ScreenBody, ScreenHeader } from '@/components/ui';
 import { toFa } from '@/lib/format';
+import { useCompanion } from '@/state/companion';
 
 /*
  * «گزارشِ والدین». تا ۱۴۰۵-۰۷ والد حسابِ جدا و کدِ دعوت داشت؛ به خواستِ سینیور
@@ -46,7 +47,7 @@ export function ReportScreen() {
         subtitle={`پیشرفتِ ${profile.name || 'دانش‌آموز'} در ۷ روزِ اخیر`}
         color={THIS_WEEK}
         back
-        mascot={{ char: 'sigma', mood: 'happy', size: 56 }}
+        mascot={{ mood: 'happy', size: 56 }}
       />
       <ScreenBody className="flex flex-col gap-4">
         {report.loading ? (
@@ -143,9 +144,10 @@ function verdict(now: ReportTotals, before: ReportTotals, name: string): { mood:
 
 function Verdict({ now, before, name }: { now: ReportTotals; before: ReportTotals; name: string }) {
   const { mood, text } = verdict(now, before, name);
+  const companion = useCompanion().char;
   return (
     <div className="flex items-center gap-3 rounded-3xl border border-line bg-white p-4">
-      <SeyarMascot char="sigma" mood={mood} size={52} />
+      <SeyarMascot char={companion} mood={mood} size={52} />
       <p className="flex-1 text-sm font-bold leading-7 text-ink">{text}</p>
     </div>
   );