fix(normalizer): don't convert plausible typo years as Excel serials

tools/import-normalizer/tests/test_persons_tree.py

@@ -52,3 +52,10 @@ def test_parse_year_unresolvable_truncated():
 def test_parse_year_typo_year():
     # "4.3.1023" — year 1023 outside 1500-2100 guard — returns None
     assert persons_tree._parse_year("4.3.1023") is None
+
+
+def test_parse_year_bare_out_of_range_year_is_none():
+    # "1023" is a plausible typo for "1923" but is NOT an Excel serial.
+    # parse_date("1023") parses it as year 1023 (out of 1700-2100 guard).
+    # The serial branch must NOT re-interpret it as a serial.
+    assert persons_tree._parse_year("1023") is None