feat(mobile): supabase client wired through async-storage session

apps/mobile/lib/supabase.ts

@@ -0,0 +1,16 @@
+import { createClient } from '@chat-app/shared/supabase';
+
+import { env } from './env';
+import { sessionStorage } from './sessionStorage';
+
+// Single Supabase client instance for the mobile app. Token storage goes
+// to AsyncStorage so the session survives reboots. detectSessionInUrl is
+// false because the magic-link callback is handled by our own
+// app/auth/callback.tsx screen — Expo Router routes the deep link to
+// that file, and we parse it explicitly.
+export const supabase = createClient({
+  url: env.supabaseUrl,
+  anonKey: env.supabaseAnonKey,
+  sessionStorage,
+  detectSessionInUrl: false,
+});