feat(ui): wire the chip-pack purchase to Robokassa

Replace the disabled "Soon" pack action with a real purchase: the Wallet opens a
money order (wallet.order) and sends the player to the provider's hosted-payment
page (window.open via openExternalUrl); the chips are credited later by the
verified server callback. Add a public-offer link under the packs (paying
accepts the offer). Codec order round-trip unit test + a mock-e2e purchase test;
the Google Play stub and the chip-spend paths are unchanged.

ui/src/lib/transport.ts

@@ -237,6 +237,9 @@ export function createTransport(baseUrl: string): GatewayClient {
     async walletBuy(productId: string) {
       return codec.decodeWallet(await exec('wallet.buy', codec.encodeWalletBuy(productId)));
     },
+    async walletOrder(productId: string) {
+      return codec.decodeWalletOrder(await exec('wallet.order', codec.encodeWalletOrder(productId)));
+    },
 
     async friendsList() {
       return codec.decodeFriendList(await exec('friends.list', codec.empty()));