feat: add freshness decay to tackle analytics

apps/api/app/routers/analytics.py

@@ -2,6 +2,7 @@ from __future__ import annotations
 
 from collections import defaultdict
 from datetime import datetime, timedelta, timezone
+from math import exp, log
 
 from fastapi import APIRouter, Query
 from sqlalchemy import select
@@ -12,6 +13,12 @@ from ..models import CatchReport, Fish, ModerationStatus, Spot, Waterbody
 from ..schemas import TackleCombinationOut
 
 router = APIRouter()
+FRESHNESS_HALF_LIFE_HOURS = 12.5
+
+
+def _age_hours(value: datetime, now: datetime) -> float:
+    observed_at = value if value.tzinfo is not None else value.replace(tzinfo=timezone.utc)
+    return max(0.0, (now - observed_at).total_seconds() / 3600)
 
 
 @router.get("/api/v1/analytics/tackle", response_model=list[TackleCombinationOut])
@@ -53,14 +60,19 @@ def tackle_combinations(
         catches = len(unique_reports)
         unique_players = len(players)
         last_seen = max(report.reported_at for report in unique_reports.values())
+        freshness_score = round(sum(
+            exp(-_age_hours(report.reported_at, now) * log(2) / FRESHNESS_HALF_LIFE_HOURS)
+            for report in unique_reports.values()
+        ) / catches * 100)
         enough = catches >= min_samples and unique_players >= min_players
         result.append(TackleCombinationOut(
             role=role, value=value, catches=catches, unique_players=unique_players,
-            last_seen_at=last_seen, status="recommendation" if enough else "insufficient_data",
+            last_seen_at=last_seen, freshness_score=freshness_score,
+            status="recommendation" if enough else "insufficient_data",
             explanation=(
                 "Достаточно независимых наблюдений для рекомендации."
                 if enough else
                 f"Данных мало: нужно минимум {min_samples} наблюдения и {min_players} независимых игрока."
             ),
         ))
-    return sorted(result, key=lambda item: (item.status != "recommendation", -item.catches, -item.unique_players, item.role, item.value))
+    return sorted(result, key=lambda item: (item.status != "recommendation", -item.freshness_score, -item.catches, -item.unique_players, item.role, item.value))