stop poisoning the unit suite from Room teardown races

The ThemeTest failure was cross-test contamination, not a theme bug. A Room invalidation-tracker query keeps running on a cancelled flow collector after the in-memory DB is closed or finalised, throws "no such table: sources", and kotlinx-coroutines-test records it and fails the next Compose test with UncaughtExceptionsBeforeTest. Which test it lands on is just ordering/load luck.

Close repositories the way DownloadRepository already did: cancel and join the scope, so Room work cannot outlive close. Stop closing the in-memory test DBs; the DB is dropped and collected once the test releases it, instead of being torn down under a pending query. Wait for the stored ref in offlineModeStillServesDownloadedArtwork instead of asserting once, since it was waiting on a different flow than the state coverArt reads. Print full stack traces for failed tests in CI.

app/build.gradle.kts

@@ -1,3 +1,4 @@
+import org.gradle.api.tasks.testing.logging.TestExceptionFormat
 import org.jetbrains.kotlin.gradle.dsl.JvmTarget
 
 plugins {
@@ -100,6 +101,13 @@ tasks.withType<Test>().configureEach {
             integrationTestClasses.forEach { excludeTestsMatching(it) }
         }
     }
+    testLogging {
+        exceptionFormat = TestExceptionFormat.FULL
+        events("failed")
+        showStackTraces = true
+        showExceptions = true
+        showCauses = true
+    }
 }
 
 tasks.register<Test>("integrationTest") {