fix(tradein): review minors — ceiling_height_m numeric(5,2) + strengthen finishing test

- Migration 111: ceiling_height_m numeric → numeric(5,2) (schema consistency with living_area_m2/kitchen_area_m2)
- test_finishing_stored_lowercase_stripped: fixture now uses padded uppercase '  Чистовая  ' to actually exercise .strip().lower(), asserts finishing == 'чистовая'

tradein-mvp/backend/data/sql/111_listings_avito_detail_fields.sql

@@ -11,7 +11,7 @@
 
 BEGIN;
 
-ALTER TABLE listings ADD COLUMN IF NOT EXISTS ceiling_height_m numeric;
+ALTER TABLE listings ADD COLUMN IF NOT EXISTS ceiling_height_m numeric(5,2);
 ALTER TABLE listings ADD COLUMN IF NOT EXISTS finishing text;
 
 COMMIT;

tradein-mvp/backend/tests/test_avito_detail_parse.py

@@ -303,12 +303,12 @@ def test_finishing_stored_lowercase_stripped() -> None:
     <div data-marker="item-view/item-id">№ 8888888888</div>
     <span itemprop="price" content="5000000">5 000 000 ₽</span>
     <div data-marker="item-view/item-params">
-      <ul><li>Отделка: под ключ</li></ul>
+      <ul><li>Отделка:   Чистовая  </li></ul>
     </div>
     </body></html>
     """
     result = parse_detail_html(html, "https://www.avito.ru/test_8888888888")
-    assert result.finishing == "под ключ"
+    assert result.finishing == "чистовая"
 
 
 # ── _parse_height_m unit tests ────────────────────────────────────────────────