fix(payments): VK-iOS freeze is purchase-only; remove the rewarded diagnostic

Testing the rewarded slice surfaced a contradiction: rewarded ads let a VK-iOS
user earn vk chips, but the blanket VK-iOS "spend freeze" then blocked spending
them (the wallet showed "5 (view-only)"). Apple's ToS forbids only BUYING in-app
values on VK-iOS (money -> chips), not spending or earning them — so the freeze is
corrected to purchase-only: vkFrozen() now gates only CreateOrder (the money-in
step), not spendableSources (spending). VK-wallet chips — earned via rewarded ads
or bought on the same account elsewhere (VK Android) — now spend on VK-iOS too.
(Owner's ToS finding.)

Also: the temporary contour diagnostic confirmed VK returns only {result:true} for
a rewarded view (no token/signature) — client-attested is final, no hardening
possible — so the diagnostic (the log and the diag wire field) is removed.

Docs: PAYMENTS(+ru) VK-iOS freeze + D17 amend + PLAN E6. Tests updated (gate /
wallet VK-iOS now spendable).

ui/src/lib/ads.ts

@@ -17,12 +17,10 @@ export function adsStubEnabled(): boolean {
   return (import.meta.env as Record<string, string | undefined>).VITE_ADS_STUB === '1';
 }
 
-/** RewardedResult is one rewarded-ad view: whether it was watched, the raw provider result as JSON
- *  (forwarded for the contour diagnostic), and whether it was the test stub (so the caller can show
- *  the "ad fired" marker toast). */
+/** RewardedResult is one rewarded-ad view: whether it was watched, and whether it was the test stub
+ *  (so the caller can show the "ad fired" marker toast). */
 export interface RewardedResult {
   watched: boolean;
-  data: string;
   stub: boolean;
 }
 
@@ -44,8 +42,7 @@ export async function rewardedReady(): Promise<boolean> {
  */
 export async function showRewarded(): Promise<RewardedResult> {
   if (adsStubEnabled()) {
-    return { watched: true, data: JSON.stringify({ stub: true }), stub: true };
+    return { watched: true, stub: true };
   }
-  const r = await vkShowRewarded();
-  return { watched: r.watched, data: r.data, stub: false };
+  return { watched: await vkShowRewarded(), stub: false };
 }