fix: use ceiling division for PaymentDetails.amountSats

Activity list showed 222 sats while review screen showed 223 for a
222222 msat payment. The PaymentDetails extension used floor division
(amountMsat / 1000). Use ceiling to match all other display paths.

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

Author: ben-kaufman

app/src/main/java/to/bitkit/ext/PaymentDetails.kt

@@ -2,4 +2,5 @@ package to.bitkit.ext
 
 import org.lightningdevkit.ldknode.PaymentDetails
 
-val PaymentDetails.amountSats: ULong? get() = amountMsat?.let { it / 1000u }
+val PaymentDetails.amountSats: ULong?
+    get() = amountMsat?.let { (it + 999u) / 1000u }