Add MAX Mini App frontend flow

app/composables/useMessengerMiniApp.ts

@@ -0,0 +1,45 @@
+import { decodeMessengerMiniAppStartParam } from '~/composables/useMessengerMiniAppStart';
+
+export function useMessengerMiniApp() {
+  const telegramMiniApp = useTelegramMiniApp();
+  const maxMiniApp = useMaxMiniApp();
+
+  const channel = computed<'TELEGRAM' | 'MAX' | null>(() => {
+    if (maxMiniApp.isAvailable.value) {
+      return 'MAX';
+    }
+
+    if (telegramMiniApp.isAvailable.value) {
+      return 'TELEGRAM';
+    }
+
+    return null;
+  });
+
+  const isAvailable = computed(() => channel.value !== null);
+  const initData = computed(() =>
+    channel.value === 'MAX' ? maxMiniApp.initData.value : telegramMiniApp.initData.value,
+  );
+  const startParam = computed(() =>
+    channel.value === 'MAX' ? maxMiniApp.startParam.value : telegramMiniApp.startParam.value,
+  );
+  const startPath = computed(() => decodeMessengerMiniAppStartParam(startParam.value));
+  const displayName = computed(() =>
+    channel.value === 'MAX' ? maxMiniApp.displayName.value : telegramMiniApp.displayName.value,
+  );
+  const channelLabel = computed(() =>
+    channel.value === 'MAX' ? 'MAX' : channel.value === 'TELEGRAM' ? 'Telegram' : '',
+  );
+
+  return {
+    channel,
+    channelLabel,
+    isAvailable,
+    initData,
+    startParam,
+    startPath,
+    displayName,
+    telegramMiniApp,
+    maxMiniApp,
+  };
+}