feat(iap): native Myket in-app billing plugin (AIDL) + wire purchase/consume

Implements real Myket IAB for the Capacitor app (Myket has no purchase
deep-link like Bazaar — it uses the classic Google Play IAB v3 AIDL bound to
the Myket app):

- AIDL: com.android.vending.billing.IInAppBillingService (Myket-compatible).
- MyketBillingPlugin (Capacitor): binds ir.mservices.market via
  "ir.mservices.market.InAppBillingService.BIND", runs getBuyIntent →
  startIntentSenderForResult, verifies INAPP_DATA_SIGNATURE with the RSA key
  (Security.java, SHA1withRSA), returns the purchaseToken; consume() too.
- MainActivity registers the plugin + forwards the purchase activity result.
- Manifest: ir.mservices.market.BILLING permission + <queries> for Android 11+
  package visibility.
- build.gradle: enable buildFeatures.aidl (AGP 8 disables it by default).
- storeBilling: Myket goes through the plugin (RSA key embedded); after server
  verify, BuyCoins consumes the purchase so coins can be re-bought.

Bazaar (deep-link) and web (ZarinPal) paths unchanged. Needs on-device testing
with the Myket app installed + published products.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/components/screens/BuyCoinsScreen.tsx

@@ -6,7 +6,7 @@ import { ScreenHeader, ScreenShell } from "@/components/online/ScreenHeader";
 import { useSessionStore } from "@/lib/session-store";
 import { useI18n } from "@/lib/i18n";
 import { getService } from "@/lib/online/service";
-import { isStoreBilling, purchaseViaStore } from "@/lib/storeBilling";
+import { consumeStorePurchase, isStoreBilling, purchaseViaStore } from "@/lib/storeBilling";
 import { sound } from "@/lib/sound";
 import { CoinPack } from "@/lib/online/types";
 import { cn } from "@/lib/cn";
@@ -47,6 +47,8 @@ export function BuyCoinsScreen() {
         if (r.kind === "token") {
           const v = await getService().verifyIab(r.store, r.productId, r.token);
           if (v.ok && v.profile) {
+            // Consumable: let the store mark it consumed so it can be re-bought.
+            await consumeStorePurchase(r.store, r.token);
             setProfile(v.profile);
             sound.play("purchase");
             setGained(v.coins);

src/lib/storeBilling.ts

@@ -4,13 +4,14 @@
 //   `bazaar://in_app?...&sku=...&redirect_url=...`; Bazaar processes payment and
 //   reopens the app at redirect_url with `?purchaseToken=...`. We stash the SKU
 //   first, then on return POST the token to `/api/coins/iab/verify`.
-// - **Myket**: native AIDL billing. A Capacitor plugin must inject
-//   `window.MyketBilling` (see ANDROID.md). We call `.purchase(sku)` and POST the
-//   returned token to verify. Without the bridge, Myket is "unavailable".
+// - **Myket**: native AIDL billing via the `MyketBilling` Capacitor plugin
+//   (android/.../billing/MyketBillingPlugin.java). We call `.purchase({sku})`,
+//   POST the returned token to verify, then `.consume({token})` so the
+//   consumable can be bought again.
 //
-// The active store is the build flavor `NEXT_PUBLIC_STORE` (bazaar|myket|web),
-// overridden at runtime if the Myket native bridge is present.
+// The active store is the build flavor `NEXT_PUBLIC_STORE` (bazaar|myket|web).
 
+import { registerPlugin } from "@capacitor/core";
 import { CoinPack } from "./online/types";
 
 export type StoreId = "bazaar" | "myket" | "web";
@@ -19,24 +20,30 @@ const ENV_STORE = ((process.env.NEXT_PUBLIC_STORE as StoreId | undefined) ?? "we
 const PACKAGE = process.env.NEXT_PUBLIC_APP_PACKAGE ?? "com.bargevasat.app";
 const PENDING_SKU_KEY = "iab_pending_sku";
 
-/** Native bridge contract a Myket Capacitor plugin must fulfil. */
-interface MyketBridge {
-  available?: boolean;
-  purchase: (sku: string) => Promise<{ purchaseToken: string; productId?: string }>;
-  consume?: (token: string) => Promise<void>;
+// Myket in-app billing RSA public key (Myket developer panel). Public, not secret.
+const MYKET_RSA_PUBLIC_KEY =
+  "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCbUBKRU4g1AQrbOO8GkcBn79ol0hbs5PZVd5vPP6za98BTc9leqvyGE+DwSg7lbsXTZxCzPRBS3m0qB9LShe70WG+RQapG9Q2lodszYkauicPkJSpbXWh/nfrziTWNqEHqUfCsC4+lkKSEkxDNa1Po7uZzbwaJ+Kf1+d8wSWYpxwIDAQAB";
+
+interface MyketBillingPlugin {
+  isAvailable(): Promise<{ available: boolean }>;
+  connect(opts: { rsaPublicKey: string }): Promise<void>;
+  purchase(opts: { sku: string; rsaPublicKey: string }): Promise<{
+    purchaseToken: string;
+    productId?: string;
+  }>;
+  consume(opts: { token: string }): Promise<void>;
 }
+const MyketBilling = registerPlugin<MyketBillingPlugin>("MyketBilling");
+
 declare global {
   interface Window {
-    MyketBilling?: MyketBridge;
     Capacitor?: { isNativePlatform?: () => boolean; getPlatform?: () => string };
   }
 }
 
 export function getStore(): StoreId {
   if (typeof window === "undefined") return ENV_STORE;
-  // Myket's native bridge wins when present (a Myket-flavored build).
-  if (window.MyketBilling?.available) return "myket";
-  // Honor an explicit build flavor.
+  // Honor an explicit build flavor (bazaar | myket).
   if (ENV_STORE !== "web") return ENV_STORE;
   // Otherwise, inside the Android app shell (Capacitor) default to Cafe Bazaar
   // IAB — the APK ships to Bazaar, which requires its own billing. The web build
@@ -77,14 +84,32 @@ export async function purchaseViaStore(pack: CoinPack): Promise<PurchaseStart> {
     return { kind: "redirect" };
   }
 
-  if (store === "myket" && window.MyketBilling) {
-    const res = await window.MyketBilling.purchase(sku);
-    return { kind: "token", store: "myket", productId: res.productId ?? sku, token: res.purchaseToken };
+  if (store === "myket") {
+    try {
+      const res = await MyketBilling.purchase({ sku, rsaPublicKey: MYKET_RSA_PUBLIC_KEY });
+      return { kind: "token", store: "myket", productId: res.productId ?? sku, token: res.purchaseToken };
+    } catch {
+      return { kind: "unavailable" };
+    }
   }
 
   return { kind: "unavailable" };
 }
 
+/**
+ * Finalize a verified store purchase. Coin packs are consumable, so on Myket we
+ * must consume the purchase (after the server credited it) to allow re-buying.
+ * Bazaar consumables are handled server-side; this is a no-op there.
+ */
+export async function consumeStorePurchase(store: StoreId, token: string): Promise<void> {
+  if (store !== "myket" || !token) return;
+  try {
+    await MyketBilling.consume({ token });
+  } catch {
+    /* best-effort; the server already credited */
+  }
+}
+
 /**
  * On app load, capture a Bazaar redirect (`?purchaseToken=...`). Returns the
  * pending purchase to verify, or null. Also clears the stashed SKU.