Normalize aggregate result words to lowercase (#835)

* fix: normalize aggregate result words

Normalize policy-evaluated and authentication result values so mixed-case reporter output does not create duplicate categories. Add a regression covering the existing uppercase sample.

* Move changelog entry to the Unreleased section

The entry landed in the released 10.2.4 section because the branch was
cut before the Unreleased heading existed on master; merged master and
moved it under Unreleased -> Bug fixes, matching the house entry style.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* Apply review feedback: normalize disposition, share a guarded helper

- policy_evaluated disposition gets the same lowercase normalization as
  dkim/spf and the auth result words; the RFC 7489 Appendix C /
  RFC 9990 disposition enum is lowercase (none/quarantine/reject), and
  mixed-case values split the Message Disposition categories in every
  dashboard the same way Pass/pass did.
- All four normalization sites now share _normalize_result_word(),
  which guards with isinstance(str): xmltodict returns a dict for
  attribute-bearing elements, so the previously unguarded .lower()
  calls on auth results could raise AttributeError on malformed input
  that used to pass through.
- The #520 fixture's disposition is now mixed-case (None) and the test
  asserts it parses as "none"; verified the assertion fails against the
  pre-fix parser. Test docstring cites the RFC authority per the
  project's testing standards.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

---------

Co-authored-by: Sean Whalen <44679+seanthegeek@users.noreply.github.com>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

tests/test_init.py

@@ -166,6 +166,25 @@ class Test(unittest.TestCase):
                 )
             print("Passed!")
 
+    def testAggregateResultWordsAreLowercase(self):
+        """Reporter-supplied result words are lowercased at ingest; RFC 7489
+        Appendix C and RFC 9990 define the result and disposition types as
+        lowercase enum tokens (issue #288).
+        """
+        result = parsedmarc.parse_report_file(
+            "samples/aggregate_invalid/report_with_upper_cased_pass.xml",
+            offline=True,
+        )
+        assert result["report_type"] == "aggregate"
+        report = cast(AggregateReport, result["report"])
+        record = report["records"][0]
+
+        self.assertEqual(record["policy_evaluated"]["dkim"], "pass")
+        self.assertEqual(record["policy_evaluated"]["spf"], "pass")
+        self.assertEqual(record["auth_results"]["dkim"][0]["result"], "pass")
+        self.assertEqual(record["auth_results"]["spf"][0]["result"], "pass")
+        self.assertEqual(record["policy_evaluated"]["disposition"], "none")
+
     def testEmptySample(self):
         """Test empty/unparasable report"""
         with self.assertRaises(parsedmarc.ParserError):