Classify the landlord Age column into a construction-age-band category 🟥

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tests/applications/landlord_description_overrides/test_build_columns.py

@@ -38,3 +38,16 @@ def test_build_columns_wires_a_glazing_classifier_column() -> None:
     assert len(columns) == 1
     assert columns[0].name == "glazing"
     assert columns[0].source_column == "Glazing"
+
+
+def test_build_columns_wires_a_construction_age_band_classifier_column() -> None:
+    # Arrange
+    chat_gpt = cast(ChatGPT, object())
+
+    # Act
+    columns = _build_columns({"construction_age_band": "Age"}, chat_gpt, None)
+
+    # Assert — one column, named construction_age_band, reading the "Age" header.
+    assert len(columns) == 1
+    assert columns[0].name == "construction_age_band"
+    assert columns[0].source_column == "Age"