fix(yandex-valuation): use curl_cffi chrome120 — Yandex gates SSR on Chrome TLS

Live probe today: plain httpx GET to /otsenka-kvartiry-po-adresu-onlayn/
returns 200 OK with full HTML, but body contains only the table header row
(__head). Data rows are CSR-rendered. curl_cffi with impersonate=chrome120
gets full SSR (21 rows, 133 cells, 38 dates verified).

Override __aenter__/__aexit__/_http_get only in YandexValuationScraper —
BaseScraper untouched (other scrapers don't need Chrome TLS).

Sibling pattern: yandex_realty.py + scripts/local-sweep-ekb-yandex.py
already use curl_cffi chrome120. This brings yandex_valuation in line.

Net effect: DOM-based parser from PR #544 will actually have DOM rows to
parse. Previous re-sweep returned 0 saves because rows weren't in SSR.

tradein-mvp/backend/app/services/scrapers/yandex_valuation.py

@@ -22,6 +22,7 @@ from datetime import date
 from typing import Any
 from urllib.parse import urlencode
 
+from curl_cffi.requests import AsyncSession as _CurlCffiSession
 from pydantic import BaseModel, Field
 from selectolax.parser import HTMLParser
 
@@ -158,6 +159,31 @@ class YandexValuationScraper(BaseScraper):
     def __init__(self) -> None:
         super().__init__()
         self.request_delay_sec = get_scraper_delay(self.name)
+        self._cffi_session: _CurlCffiSession | None = None
+
+    async def __aenter__(self) -> YandexValuationScraper:  # type: ignore[override]
+        # Override: Yandex valuation endpoint gates SSR data on Chrome TLS
+        # fingerprint. Plain httpx returns shell HTML (CSR-only).
+        # Sibling: yandex_realty.py / scripts/local-sweep-ekb-yandex.py
+        self._cffi_session = _CurlCffiSession(impersonate="chrome120")
+        return self
+
+    async def __aexit__(self, *args: object) -> None:  # type: ignore[override]
+        if self._cffi_session is not None:
+            await self._cffi_session.close()
+            self._cffi_session = None
+
+    async def _http_get(self, url: str, **kwargs: object) -> object:  # type: ignore[override]
+        """curl_cffi-based GET with Chrome120 impersonation.
+
+        Returns curl_cffi Response (compatible API: .status_code, .text).
+        Caller must check status_code; no automatic retry (BaseScraper.retry
+        decorator is per-method and not inherited cleanly when overridden).
+        """
+        if self._cffi_session is None:
+            raise RuntimeError("YandexValuationScraper must be used as async context manager")
+        kwargs.setdefault("timeout", 30)
+        return await self._cffi_session.get(url, **kwargs)
 
     async def fetch_around(self, lat: float, lon: float, radius_m: int = 1000) -> list:  # type: ignore[override]
         raise NotImplementedError(