Add a fourth failing @FailsOnEmulatorApi37 test, to prove the report fires

#83's acceptance: a comparison that cannot be shown to fire is not a comparison.
This branch is the mutation, and it is thrown away as soon as the run reports.
The advisory job should say expected 4, failed 4, against a baseline of 3, emit
::notice:: for each, and finish with its conclusion unchanged -- red, advisory,
and not a required context, exactly as before.

The gating API 37 leg must be untouched by it: the probe carries the marker, and
that leg selects on notAnnotation.

app/src/androidTest/java/org/libremediaconverter/MutationProbeApi37Test.kt

@@ -0,0 +1,22 @@
+package org.libremediaconverter
+
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import org.junit.Assert.fail
+import org.junit.Test
+import org.junit.runner.RunWith
+
+/**
+ * TEMPORARY. This file exists only to prove #83's report fires, and is deleted immediately after.
+ *
+ * It is the mutation the ticket asks for: a fourth test carrying [FailsOnEmulatorApi37] that
+ * fails. The advisory job should report `expected 4` and `failed 4` against a baseline of 3, say
+ * so as a `::notice::`, and finish with its conclusion unchanged.
+ */
+@RunWith(AndroidJUnit4::class)
+class MutationProbeApi37Test {
+    @Test
+    @FailsOnEmulatorApi37
+    fun failsOnPurposeToProveTheAdvisoryReportFires() {
+        fail("mutation probe for #83 -- this test exists to fail")
+    }
+}