fix(activity): show Convert transactions in the feed

apps/flipcash/core/src/main/kotlin/com/flipcash/app/core/feed/ActivityFeedMessage.kt

@@ -9,9 +9,16 @@ import kotlinx.serialization.Serializable
 import kotlinx.serialization.json.Json
 import kotlin.time.Instant
 
+/**
+ * A feed entry paired with the token metadata its row needs.
+ *
+ * [token] is the entry's own token (for a convert, the source side). [toToken] is only set for a
+ * convert, which spans two mints and draws both logos; everything else leaves it null.
+ */
 data class ActivityFeedMessageWithToken(
     val message: ActivityFeedMessage,
-    val token: Token?
+    val token: Token?,
+    val toToken: Token? = null,
 )
 
 data class ActivityFeedMessage(

apps/flipcash/features/balance/src/test/kotlin/com/flipcash/app/balance/internal/WalletLoadingStateTest.kt

@@ -28,6 +28,7 @@ class WalletLoadingStateTest {
         avatar = TransactionAvatar.Generic,
         signedAmountPrefix = "+",
         amount = null,
+        fee = null,
         canCancel = false,
     )