fix: actually start BalancesUpdateSystem in the full-architecture test

First run of this test produced zero BalancesDiag output at all - not even a
single balancesSync() call for any chain. Root cause: BalancesUpdateSystem.start()
is a cold flow only ever collected by RootInteractor, which is wired to the root
Activity/ViewModel lifecycle. This bare instrumented test never launches that
Activity, so the pipeline was never started - the test's own timeout, not the
production bug, explained the failure. Now collect the same AssetsFeatureApi.
updateSystem instance directly instead of relying on app UI lifecycle.

app/src/androidTest/java/io/novafoundation/nova/balances/PezkuwiFullArchitectureBalancesTest.kt

@@ -8,8 +8,10 @@ import io.novafoundation.nova.core_db.dao.AssetDao
 import io.novafoundation.nova.core_db.dao.MetaAccountDao
 import io.novafoundation.nova.core_db.di.DbApi
 import io.novafoundation.nova.core_db.model.chain.account.MetaAccountLocal
+import io.novafoundation.nova.feature_assets.di.AssetsFeatureApi
 import io.novasama.substrate_sdk_android.ss58.SS58Encoder.toAccountId
 import kotlinx.coroutines.delay
+import kotlinx.coroutines.launch
 import kotlinx.coroutines.runBlocking
 import kotlinx.coroutines.withTimeoutOrNull
 import org.junit.Assert.assertNotNull
@@ -22,6 +24,11 @@ import kotlin.time.Duration.Companion.seconds
  * is meant to answer one question with hard evidence, not speculation: does the app's real, running background
  * sync ever write an `assets` cache row for HEZ on the Pezkuwi Asset Hub chain, for a real, well-funded account?
  *
+ * BalancesUpdateSystem.start() is a cold flow - in production it's only ever collected by RootInteractor,
+ * which is wired to the root Activity/ViewModel lifecycle. A bare instrumented test never launches that
+ * Activity, so we collect it ourselves here via the same AssetsFeatureApi.updateSystem instance the real app
+ * uses, instead of relying on app UI lifecycle to start it.
+ *
  * If this test fails, the failure message + logcat (tag "BalancesDiag", plus the standard per-updater error
  * logs already wired into BalancesUpdateSystem/FullSyncPaymentUpdater) shows exactly which decision branch or
  * exception is responsible - not another layer of inference from silence.
@@ -40,8 +47,13 @@ class PezkuwiFullArchitectureBalancesTest {
     private val metaAccountDao = dbApi.metaAccountDao()
     private val assetDao: AssetDao = dbApi.provideAssetDao()
 
+    private val assetsFeatureApi = FeatureUtils.getFeature<AssetsFeatureApi>(context, AssetsFeatureApi::class.java)
+
     @Test
     fun testPezkuwiAssetHubHezBalanceActuallySyncs() = runBlocking {
+        val updateSystemJob = launch { assetsFeatureApi.updateSystem.start().collect {} }
+
+        try {
             val metaId = insertAndSelectFounderWatchAccount(metaAccountDao)
 
             val assetRow = withTimeoutOrNull(90.seconds) {
@@ -61,6 +73,9 @@ class PezkuwiFullArchitectureBalancesTest {
                     "tag 'BalancesDiag' and the standard FullSyncPaymentUpdater/StatemineAssetBalance error logs.",
                 assetRow
             )
+        } finally {
+            updateSystemJob.cancel()
+        }
     }
 
     private suspend fun insertAndSelectFounderWatchAccount(dao: MetaAccountDao): Long {