ui(zap): reorder amount-choice chips — Cashu, Lightning, on-chain

Previously the popup rendered Lightning chips first, then on-chain, then
Cashu. With recipient-capability gating in place, lead with the rail
that's both fastest and free-of-fees when available — Cashu (nutzap) —
falling back to Lightning, then on-chain. Mirrors the priority order
RailCapabilityResolver uses for the underlying capability fallback,
so the visual top-down sweep matches "best rail for this recipient that
the sender has configured".

Mechanical reorder inside ZapAmountChoicePopupContent's FlowRow — no
behaviour change beyond layout. Gear settings button stays at the end.

https://claude.ai/code/session_01MdWddiar819f8XYt5N8BjP

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

@@ -2035,6 +2035,17 @@ fun ZapAmountChoicePopupContent(
                 verticalArrangement = Arrangement.Center,
                 itemVerticalAlignment = CenterVertically,
             ) {
+                // Order: Cashu first (instant, no fees), then Lightning,
+                // then on-chain — matches the recipient-capability fallback
+                // order used elsewhere (RailCapabilityResolver) so the
+                // "happiest path" rail surfaces first for the eye.
+                nutzapAmountChoices.forEach { amountInSats ->
+                    NutzapAmountChip(
+                        amountInSats = amountInSats,
+                        onClick = { onNutzap(amountInSats) },
+                        onLongClick = onChangeAmount,
+                    )
+                }
                 zapAmountChoices.forEach { amountInSats ->
                     ZapAmountChip(
                         amountInSats = amountInSats,
@@ -2049,13 +2060,6 @@ fun ZapAmountChoicePopupContent(
                         onLongClick = onChangeAmount,
                     )
                 }
-                nutzapAmountChoices.forEach { amountInSats ->
-                    NutzapAmountChip(
-                        amountInSats = amountInSats,
-                        onClick = { onNutzap(amountInSats) },
-                        onLongClick = onChangeAmount,
-                    )
-                }
                 ClickableBox(
                     modifier =
                         Modifier