B2: tolerant JSON extraction from Claude responses + graceful fallback

_extract_json_payload handles a json/JSON/bare fence, raw JSON and JSON
embedded in prose; any unparseable response or contract violation now
degrades to the deterministic scoring_service instead of raising.
Also guards the response envelope itself (content[0].text).

B3: single home for recommendation scoring

services/recommendation_service.py holds the rules; routers/stats.py and
backend/services/stats_service.py both delegate to it. Unified rules are the
union of the two old copies: same weights/threshold, substring matching
(superset of the old exact match), tolerant key aliases, health_flags rule
kept. Endpoint response contract unchanged.

Plus: Overpass circuit breaker and concurrent zone queries in geo_service -
128 sequential calls per analysis no longer each burn a connect timeout when
the host has no outbound network.

Tests: 152 -> 194 passed.

backend/routers/stats.py

@@ -2,6 +2,7 @@ from fastapi import APIRouter
 
 from backend.database import db
 from backend.schemas import DashboardResponse, RecommendationRequest
+from services.recommendation_service import score_recommendation
 
 router = APIRouter(prefix='/api/v1/stats', tags=['stats'])
 
@@ -18,18 +19,14 @@ def stats_heatmap() -> dict:
 
 @router.post('/recommendation')
 def stats_recommendation(payload: RecommendationRequest) -> dict:
-    score = 0
-    if payload.age is not None and payload.age < 12:
-        score += 20
-    if payload.elapsed_hours is not None and payload.elapsed_hours >= 12:
-        score += 20
-    if payload.terrain_primary in {'лес', 'болото', 'вода'}:
-        score += 15
-    if payload.weather in {'дождь', 'туман', 'снег', 'ночь'}:
-        score += 15
-    if len(payload.health_flags) >= 2:
-        score += 15
+    result = score_recommendation(
+        age=payload.age,
+        elapsed_hours=payload.elapsed_hours,
+        terrain=payload.terrain_primary,
+        weather=payload.weather,
+        health_flags=payload.health_flags,
+    )
     return {
-        'recommendation': 'Высокий приоритет на прочёс и дрон' if score >= 40 else 'Стандартный приоритет поиска',
-        'score': score,
+        'recommendation': result['recommendation'],
+        'score': result['score'],
     }