feat: hide on-chain wallet from zap buttons too

Extend the showOnchainWallet preference to the zap flows, which also surface an
on-chain rail:

- the on-chain rail on each zap-amount chip in ZapAmountChoicePopup (folded into
  the shared railCapability so every caller — reaction row, ReusableZapButton —
  is covered)
- the "Send on-chain instead" hand-off button in the custom zap dialog

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UM57Rq5iUPL1SGhzhzTusa

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/note/ReactionsRow.kt

@@ -2067,11 +2067,16 @@ fun ZapAmountChoicePopup(
     val cashuEntries by cashuState.tokenEntries.collectAsStateWithLifecycle()
     val recipientInfo = author?.let { observeUserInfo(it, accountViewModel).value }
     val nutzapInfo = author?.let { observeNoteEvent<NutzapInfoEvent>(it.nutzapInfoNote, accountViewModel).value }
+    // Honors the user's "show on-chain wallet" preference: off hides the on-chain
+    // rail from the zap chips too, matching the wallet screen, profile chips, and
+    // Send Payment screen.
+    val showOnchainWallet by accountViewModel.settings.uiSettingsFlow.showOnchainWallet
+        .collectAsStateWithLifecycle()
 
     val railCapability =
-        remember(baseNote, onchainSupported, cashuMints, cashuEntries, recipientInfo, nutzapInfo) {
+        remember(baseNote, onchainSupported, showOnchainWallet, cashuMints, cashuEntries, recipientInfo, nutzapInfo) {
             val rc = RailCapabilityResolver.peek(baseNote, cashuState)
-            if (onchainSupported) rc else rc.copy(hasOnchain = false)
+            if (onchainSupported && showOnchainWallet) rc else rc.copy(hasOnchain = false)
         }
     val amountChoices =
         remember(zapAmountChoices) {

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/note/ZapCustomDialog.kt

@@ -71,6 +71,7 @@ import androidx.compose.ui.window.Dialog
 import androidx.compose.ui.window.DialogProperties
 import androidx.core.net.toUri
 import androidx.lifecycle.ViewModel
+import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import androidx.lifecycle.viewmodel.compose.viewModel
 import com.vitorpamplona.amethyst.R
 import com.vitorpamplona.amethyst.model.Account
@@ -180,6 +181,11 @@ fun ZapCustomDialog(
     // payment method, no "go back to Lightning" is offered here.
     var sendOnchain by remember { mutableStateOf(false) }
 
+    // Hides the "Send on-chain instead" hand-off when the user has turned the
+    // on-chain wallet off, matching every other on-chain surface.
+    val showOnchainWallet by accountViewModel.settings.uiSettingsFlow.showOnchainWallet
+        .collectAsStateWithLifecycle()
+
     Dialog(
         onDismissRequest = { onClose() },
         properties =
@@ -353,16 +359,18 @@ fun ZapCustomDialog(
                 // Hand off to the on-chain dialog with the entered amount +
                 // message prefilled. Disabled while the amount is empty so the
                 // user can't open a sheet that immediately gates on its own
-                // empty field.
-                TextButton(
-                    onClick = { sendOnchain = true },
-                    enabled = postViewModel.canSend() && !baseNote.isDraft(),
-                    modifier =
-                        Modifier
-                            .fillMaxWidth()
-                            .padding(top = 4.dp),
-                ) {
-                    Text(text = stringRes(id = R.string.send_onchain_instead))
+                // empty field. Hidden entirely when the on-chain wallet is off.
+                if (showOnchainWallet) {
+                    TextButton(
+                        onClick = { sendOnchain = true },
+                        enabled = postViewModel.canSend() && !baseNote.isDraft(),
+                        modifier =
+                            Modifier
+                                .fillMaxWidth()
+                                .padding(top = 4.dp),
+                    ) {
+                        Text(text = stringRes(id = R.string.send_onchain_instead))
+                    }
                 }
             }
         }