fix(sf-07): use median_12m from mv_quarter_price_per_m2 for district price

ekb_districts.median_price_per_m2 was populated from a 24-month window.
LEFT JOIN mv_quarter_price_per_m2 on the cad quarter and COALESCE(median_12m,
fallback) so the API returns the 12-month median where available.
Frontend OverviewTab adds a "(12 мес)" hint next to the value.

Closes #271 item 7

backend/app/api/v1/parcels.py

@@ -1188,16 +1188,20 @@ def analyze_parcel(
     geom_wkt: str = geom_row["wkt"]  # type: ignore[index]
 
     # 2) District context — ближайший район ЕКБ
+    # median_price_per_m2: предпочитаем median_12m из mv_quarter_price_per_m2 (12 мес),
+    # fallback на ekb_districts.median_price_per_m2 (24 мес).
     district_row = (
         db.execute(
             text("""
-            SELECT district_name,
-                   median_price_per_m2,
+            SELECT d.district_name,
+                   COALESCE(mq.median_12m, d.median_price_per_m2) AS median_price_per_m2,
                    ST_Distance(
                        d.geom::geography,
                        ST_Centroid(ST_GeomFromText(:wkt, 4326))::geography
                    ) AS dist_to_center
               FROM ekb_districts d
+              LEFT JOIN mv_quarter_price_per_m2 mq
+                     ON mq.quarter_cad_number = REGEXP_REPLACE(:cad_num, ':[^:]+$', '')
              WHERE ST_DWithin(
                        d.geom::geography,
                        ST_Centroid(ST_GeomFromText(:wkt, 4326))::geography,
@@ -1206,7 +1210,7 @@ def analyze_parcel(
              ORDER BY dist_to_center ASC
              LIMIT 1
         """),
-            {"wkt": geom_wkt},
+            {"wkt": geom_wkt, "cad_num": cad_num},
         )
         .mappings()
         .first()

frontend/src/components/site-finder/OverviewTab.tsx

@@ -77,6 +77,7 @@ export function OverviewTab({ data, onIsochronesResult }: Props) {
             <strong style={{ color: "#374151" }}>
               {(data.district.median_price_per_m2 / 1000).toFixed(0)} тыс ₽/м²
             </strong>
+            <span className="text-xs text-slate-500 ml-1">(12 мес)</span>
             <span style={{ marginLeft: 12 }}>
               {(data.district.dist_to_center / 1000).toFixed(1)} км до центра
             </span>