fix(layouts): address review-bot minor items (#113 PR D)

Backend (parcels.py + layout_tz_pdf.py):
- 🟡 /best-layouts/pdf 404 handling: catch ValueError → 404
  (consistent с JSON endpoint handling геометрия не найдена)
- 🟡 XSS defense-in-depth: html.escape() для r.room_bucket,
  r.area_bin, m.room_bucket в HTML row generators

Frontend (BestLayoutsBlock.tsx):
- 🟡 data_window dates → ru-RU locale (toLocaleDateString)
- 🟢 target_total_flats clamped к [1, 10000] перед submit
  (paste-bypass на client защищён, backend Pydantic le=10000)

Tests: 5+27 backend pass, frontend tsc/lint/build clean.

backend/app/api/v1/parcels.py

@@ -2161,6 +2161,8 @@ async def get_parcel_best_layouts_pdf(
         )
     except HTTPException:
         raise
+    except ValueError as exc:
+        raise HTTPException(status_code=404, detail=str(exc)) from exc
     except Exception as exc:
         logger.error("best_layouts PDF endpoint failed for %s: %s", cad_num, exc)
         raise HTTPException(status_code=500, detail="Internal server error") from exc

backend/app/services/exporters/layout_tz_pdf.py

@@ -51,8 +51,8 @@ def render_layout_tz_pdf(
     top_rows = "".join(
         "<tr>"
         f"<td>{r.rank}</td>"
-        f"<td>{r.room_bucket}</td>"
-        f"<td>{r.area_bin}</td>"
+        f"<td>{_html.escape(r.room_bucket)}</td>"
+        f"<td>{_html.escape(r.area_bin)}</td>"
         f"<td>{r.velocity_per_month:.1f}</td>"
         f"<td>{r.avg_area_m2:.1f}</td>"
         f"{_price_cell(r.avg_price_per_m2_rub)}"
@@ -64,7 +64,7 @@ def render_layout_tz_pdf(
     # Recommendation mix table rows
     mix_rows = "".join(
         "<tr>"
-        f"<td>{m.room_bucket}</td>"
+        f"<td>{_html.escape(m.room_bucket)}</td>"
         f"<td>{m.pct}%</td>"
         f"<td>{m.abs_units if m.abs_units is not None else '—'}</td>"
         f"<td>{f'{m.avg_target_area_m2:.1f}' if m.avg_target_area_m2 is not None else '—'}</td>"

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

@@ -411,7 +411,8 @@ function RecommendationCard({
         <div style={{ fontSize: 11, color: "#9ca3af" }}>
           Основано на {rec.based_on_obj_count} ЖК ·{" "}
           {rec.based_on_total_deals.toLocaleString("ru-RU")} сделках · период{" "}
-          {rec.data_window_start} — {rec.data_window_end}
+          {new Date(rec.data_window_start).toLocaleDateString("ru-RU")} —{" "}
+          {new Date(rec.data_window_end).toLocaleDateString("ru-RU")}
         </div>
       </div>
     </div>
@@ -445,7 +446,10 @@ export function BestLayoutsBlock({ cadNum, selectedCompetitorObjIds }: Props) {
           ? selectedCompetitorObjIds
           : null,
       min_velocity_per_month: minVelocity,
-      target_total_flats: !Number.isNaN(parsed) && parsed > 0 ? parsed : null,
+      target_total_flats:
+        !Number.isNaN(parsed) && parsed > 0
+          ? Math.min(Math.max(parsed, 1), 10000)
+          : null,
     };
   }