core: deleting the seed reports ok, not the empty wallet

Delete re-ran /_wallet, so a successful delete printed "no wallet key",
which is the same words the error uses and reads as a failure. There is
nothing to show after a delete.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Rvc3HbiWBTqbAvRT45G5oX

src/Simplex/Chat/Library/Commands.hs

@@ -1516,7 +1516,7 @@ processChatCommand cxt nm = \case
   APIWalletDelete -> withUser $ \_ -> do
     seed <- deviceSeed
     withFastStore' $ \db -> deleteSeed db (wsId seed)
-    processChatCommand cxt nm APIWallet
+    ok_
   APISendCallInvitation contactId callType -> withUser $ \user -> do
     -- party initiating call
     ct <- withFastStore $ \db -> getContact db cxt user contactId