fix: use satsCeil for LNURL display amounts to match BOLT11 behavior

Previously LNURL-pay showed 222 sats on review but 223 after sending,
and LNURL-withdraw showed 222 while BOLT11 showed 223 for the same
222222 msat amount. Use ceiling division consistently for display.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: ben-kaufman

app/src/main/java/to/bitkit/viewmodels/AppViewModel.kt

@@ -1469,7 +1469,7 @@ class AppViewModel @Inject constructor(
         Logger.debug("LNURL: $data", context = TAG)
 
         val isFixed = data.isFixedAmount()
-        val displaySats = if (isFixed) data.maxSendableSat() else data.minSendableSat()
+        val displaySats = data.minSendableSat()
 
         if (!lightningRepo.canSend(displaySats.coerceAtLeast(1u))) {
             toast(
@@ -1528,7 +1528,7 @@ class AppViewModel @Inject constructor(
             return
         }
 
-        val displayAmount = if (isFixed) data.fixedWithdrawAmountSat() else minWithdrawable
+        val displayAmount = if (isFixed) data.minWithdrawableSat() else minWithdrawable
 
         _sendUiState.update {
             it.copy(