feat: record files a launcher never opens

unread_on names the platforms whose launcher points the emulator at other files. RetroBat writes absolute BIOS paths into standalone BlastEm's config, so the default names were reported as required and missing there. Such an entry leaves that platform's gap report and pack, and its emulator page says where it is never opened.

tests/test_audit_regressions.py

@@ -5774,5 +5774,25 @@ class TheApiSchemaHoldsTheFieldsItPromises(unittest.TestCase):
             jsonschema.validate(envelope, schema)
 
 
+class AFileTheLauncherNeverOpens(unittest.TestCase):
+    """RetroBat hands standalone BlastEm absolute paths to its own BIOS
+    names, so the defaults the emulator would read (cdbios.bin) were listed
+    as required and missing on RetroBat although nothing there opens them."""
+
+    def test_unread_on_drops_the_entry_for_that_platform_only(self):
+        from validation import deliverable, unread_on
+
+        entry = {"name": "cdbios.bin", "unread_on": ["retrobat"]}
+        self.assertTrue(unread_on(entry, "retrobat"))
+        self.assertFalse(unread_on(entry, "batocera"))
+        self.assertFalse(unread_on(entry, ""))
+        self.assertEqual(deliverable([entry], True, "retrobat"), [])
+        self.assertEqual(deliverable([entry], True, "batocera"), [entry])
+
+    def test_the_gap_report_reads_it(self):
+        source = (ROOT / "scripts" / "verify.py").read_text(encoding="utf-8")
+        self.assertIn('unread_on(f, config.get("_key", ""))', source)
+
+
 if __name__ == "__main__":
     unittest.main()