ci: show full exception detail for feature-wallet-impl unit test failures

Default Gradle test logging only prints the exception class name + one
stack frame for a failing test, not its message or cause chain - that's
exactly what happened debugging RealTronTransactionServiceTest's
InvalidTestClassError just now (console showed nothing beyond the bare
exception type). Not useful for anyone hitting a real test failure in CI
without a local Gradle run to inspect the HTML report.

feature-wallet-impl/build.gradle

@@ -27,6 +27,17 @@ android {
     }
     namespace 'io.novafoundation.nova.feature_wallet_impl'
 
+    testOptions {
+        unitTests.all {
+            testLogging {
+                events "failed"
+                exceptionFormat "full"
+                showCauses true
+                showStackTraces true
+            }
+        }
+    }
+
     buildFeatures {
         viewBinding true
     }