chore(tokens): drop the unreachable sell branch from the swap success title (#1301)

Tearing out the v1 UI removed the Sell button from the token screen, which
was the only place a SwapPurpose.Sell could be constructed. The v2 action
row offers Give, Convert, and Withdraw, so nothing can reach the success
title as a sell any more.

The title's `else` arm existed to name the reserve for that case. Make the
two reachable purposes explicit and let the fallback go unnamed rather than
claim a destination it can no longer have; the suffix was already optional.
title_cashReserves had no other reference, so it goes with it.

SwapPurpose.Sell itself stays: it is unreachable but still referenced by
SwapViewModel, AppRoute, and the sell receipt screen, so removing the type
is a larger change than this one. canSell stays too — Convert reads it.

Author: bmc08gt

apps/flipcash/core/src/main/res/values/strings.xml

@@ -532,7 +532,6 @@
     <string name="label_blendModeColorDodge">Color Dodge</string>
     <string name="label_blendModePlusLighter">Plus Lighter</string>
 
-    <string name="title_cashReserves">USDF</string>
     <string name="action_buyMore">Buy More</string>
 
     <string name="title_addMoney">Add Money</string>

apps/flipcash/features/tokens/src/main/kotlin/com/flipcash/app/tokens/internal/TokenTxProcessingScreen.kt

@@ -136,7 +136,9 @@ private fun TokenTxProcessingScreen(
                             is SwapPurpose.Convert ->
                                 state.destinationTokenName.takeUnless { state.isConvertingToDollars }
                             is SwapPurpose.BalanceIncrease -> state.tokenName
-                            else -> stringResource(R.string.title_cashReserves)
+                            // Selling is unreachable now that the v1 token screen is gone, and a
+                            // purpose is always set by the time a swap reaches this screen.
+                            else -> null
                         }
                         state.netTransferAmount.formatted(
                             suffix = name?.let { stringResource(R.string.label_ofToken, it) },