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/gen/fbs/scrabblefb/wallet-reward-request.ts

@@ -27,34 +27,22 @@ nonce(optionalEncoding?:any):string|Uint8Array|null {
   return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
 }
 
-diag():string|null
-diag(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
-diag(optionalEncoding?:any):string|Uint8Array|null {
-  const offset = this.bb!.__offset(this.bb_pos, 6);
-  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
-}
-
 static startWalletRewardRequest(builder:flatbuffers.Builder) {
-  builder.startObject(2);
+  builder.startObject(1);
 }
 
 static addNonce(builder:flatbuffers.Builder, nonceOffset:flatbuffers.Offset) {
   builder.addFieldOffset(0, nonceOffset, 0);
 }
 
-static addDiag(builder:flatbuffers.Builder, diagOffset:flatbuffers.Offset) {
-  builder.addFieldOffset(1, diagOffset, 0);
-}
-
 static endWalletRewardRequest(builder:flatbuffers.Builder):flatbuffers.Offset {
   const offset = builder.endObject();
   return offset;
 }
 
-static createWalletRewardRequest(builder:flatbuffers.Builder, nonceOffset:flatbuffers.Offset, diagOffset:flatbuffers.Offset):flatbuffers.Offset {
+static createWalletRewardRequest(builder:flatbuffers.Builder, nonceOffset:flatbuffers.Offset):flatbuffers.Offset {
   WalletRewardRequest.startWalletRewardRequest(builder);
   WalletRewardRequest.addNonce(builder, nonceOffset);
-  WalletRewardRequest.addDiag(builder, diagOffset);
   return WalletRewardRequest.endWalletRewardRequest(builder);
 }
 }