fix(tradein-api): add PlacementHistoryEntry schema + None checks

Follow-up to PR #528 review-bot Medium findings:
- /placement-history endpoint typed via new PlacementHistoryEntry schema
  (OpenAPI + Pydantic validation, consistent with other endpoints)
- Replace truthy 'if target.lat and target.lon' with 'is not None'
  (defensive against lat=0.0 in future region expansion)

tradein-mvp/backend/app/api/v1/trade_in.py

@@ -21,6 +21,7 @@ from app.schemas.trade_in import (
     HouseInfoForEstimate,
     IMVBenchmarkResponse,
     PhotoMeta,
+    PlacementHistoryEntry,
     TradeInEstimateInput,
 )
 from app.services.exporters.trade_in_pdf import generate_trade_in_pdf
@@ -418,7 +419,7 @@ def get_estimate_houses(
 
     # Path 2: geo-nearby (any source, 500м radius)
     nearby: list[Any] = []
-    if target.lat and target.lon:
+    if target.lat is not None and target.lon is not None:
         nearby = list(
             db.execute(
                 text(
@@ -453,11 +454,11 @@ def get_estimate_houses(
     ]
 
 
-@router.get("/estimate/{estimate_id}/placement-history")
+@router.get("/estimate/{estimate_id}/placement-history", response_model=list[PlacementHistoryEntry])
 def get_estimate_placement_history(
     estimate_id: UUID,
     db: Annotated[Session, Depends(get_db)],
-) -> list[dict]:
+) -> list[PlacementHistoryEntry]:
     """Историческая продажная активность по дому(ам) target estimate.
 
     Возвращает rows из house_placement_history для всех houses связанных с
@@ -490,7 +491,7 @@ def get_estimate_placement_history(
         ).all()
         house_ids = [r.id for r in rows]
 
-    if not house_ids and target.lat and target.lon:
+    if not house_ids and target.lat is not None and target.lon is not None:
         # Geo fallback: 100м (tight radius чтобы не смешать соседние дома)
         rows = db.execute(
             text(
@@ -528,7 +529,7 @@ def get_estimate_placement_history(
         {"house_ids": house_ids},
     ).mappings().all()
 
-    return [dict(r) for r in history]
+    return [PlacementHistoryEntry(**dict(r)) for r in history]
 
 
 @router.get("/estimate/{estimate_id}/imv-benchmark", response_model=IMVBenchmarkResponse)

tradein-mvp/backend/app/schemas/trade_in.py

@@ -146,6 +146,27 @@ class IMVBenchmarkResponse(BaseModel):
     diff_pct: float | None = None            # (our - imv) / imv * 100
 
 
+class PlacementHistoryEntry(BaseModel):
+    """Запись истории размещения лота в доме (`house_placement_history`)."""
+
+    id: int
+    source: str
+    house_id: int | None = None
+    ext_item_id: str
+    title: str | None = None
+    rooms: int | None = None
+    area_m2: float | None = None
+    floor: int | None = None
+    total_floors: int | None = None
+    start_price: int | None = None
+    start_price_date: date | None = None
+    last_price: int | None = None
+    last_price_date: date | None = None
+    removed_date: date | None = None
+    exposure_days: int | None = None
+    notes: str | None = None
+
+
 # ── In-app scheduler (Stage 4e) ─────────────────────────────────────────────