fix: check the event schema under the given root

validate_schemas.py read install-events.schema.json from the real tree while a test pointed ROOT at a scratch one, and test_schema_semantic_gate.py called unittest.main() before its last class.

scripts/validate_schemas.py

@@ -558,7 +558,7 @@ def _event_schema_errors() -> list[str]:
     """install-events.schema.json is EVENT_KEYS written out, and a valid schema."""
     import generate_event_schema  # noqa: PLC0415
 
-    path = generate_event_schema.OUTPUT
+    path = ROOT / "schemas" / generate_event_schema.OUTPUT.name
     label = path.relative_to(ROOT).as_posix()
     if not path.is_file():
         return [f"{label}: missing, run python scripts/generate_event_schema.py"]
@@ -567,7 +567,7 @@ def _event_schema_errors() -> list[str]:
     ):
         return [f"{label}: differs from EVENT_KEYS in install.py, run "
                 "python scripts/generate_event_schema.py"]
-    _validator(path.name)
+    Draft202012Validator.check_schema(_load_json(path))
     return []
 
 

tests/test_schema_semantic_gate.py

@@ -94,10 +94,6 @@ class SemanticManifestValidation(unittest.TestCase):
         self.assertIn("total_files does not equal len(files)", errors[0])
 
 
-if __name__ == "__main__":
-    unittest.main()
-
-
 try:
     import jsonschema
 except ImportError:
@@ -122,3 +118,7 @@ class DataRootIsKeyedBySystem(unittest.TestCase):
         self.assertTrue(self._errors({"amiga": {"path": "x", "source_ref": "y"}}))
         self.assertTrue(self._errors({"windows": {"path": "%APPDATA%/X"}}))
         self.assertTrue(self._errors({}))
+
+
+if __name__ == "__main__":
+    unittest.main()