Fix reserved fee info text display for zero amounts in staking

Previously, the reserved fee info text would display even when the input amount was zero. This change adds a check to ensure the info text only appears when the user has entered a non-zero amount that would trigger the reserved fee warning.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: DRadmir

Features/Transfer/Sources/ViewModels/AmountSceneViewModel.swift

@@ -102,8 +102,9 @@ public final class AmountSceneViewModel {
             return nil
         case .stake, .freeze:
             guard reservedForFee > .zero else { return nil }
-            guard let inputValue = try? formatter.inputNumber(from: amountInputModel.text, decimals: asset.decimals.asInt) else { return nil }
-            guard inputValue >= availableBalanceForStaking, inputValue <= availableValue else { return nil }
+            guard let inputValue = try? formatter.inputNumber(from: amountInputModel.text, decimals: asset.decimals.asInt),
+                  !inputValue.isZero, inputValue >= availableBalanceForStaking, inputValue <= availableValue
+            else { return nil }
             return Localized.Transfer.reservedFees(formatter.string(reservedForFee, asset: asset))
         }
     }

Features/Transfer/Tests/ViewModels/AmountSceneViewModelTests.swift

@@ -40,6 +40,9 @@ struct AmountSceneViewModelTests {
 
         #expect(model.infoText != nil)
         #expect(model.amountInputModel.text == "1.99975")
+        
+        model.amountInputModel.text = .zero
+        #expect(model.infoText == nil)
     }
 
     @Test