chore: add test infrastructure and update risk router

- Add vitest config and unit tests for components, api, stores
- Add Playwright e2e test for user flows
- Add backend test files
- Update risk.py with LOD grid KDTree optimization

backend/routers/risk.py

@@ -2,7 +2,7 @@
 Router for CBPOA risk assessment endpoints
 Reads from GeoJSON files in outputs/daily/ directory
 """
-from fastapi import APIRouter, HTTPException, Query
+from fastapi import APIRouter, HTTPException, Path, Query
 from datetime import datetime, timedelta
 from pathlib import Path
 from typing import Annotated, List, Literal
@@ -420,7 +420,7 @@ async def get_risk_history(grid_id: str, days: int = 7):
 
 @router.get("/forecast/{days}", response_model=RiskMapResponse)
 async def get_forecast_map(
-    days: Annotated[int, Query(ge=1, le=7, description="Forecast horizon in days")]
+    days: Annotated[int, Path(ge=1, le=7, description="Forecast horizon in days")]
 ):
     """
     Get forecast risk map for specified horizon (1, 3, or 7 days).
@@ -439,23 +439,16 @@ async def get_forecast_map(
         raise HTTPException(status_code=404, detail="No grid data found")
 
     # Adjust risk values by forecast horizon (small noise proportional to days)
-    rng = np.random.default_rng(hash(days + latest_date) % (2**31))
+    rng = np.random.default_rng(hash(str(days) + latest_date) % (2**31))
     result = []
     for g in grids[:5000]:
         adjusted = min(1.0, max(0.0, g["risk_value"] + (rng.random() - 0.5) * 0.1 * days))
-        risk_level = (
-            "high" if adjusted >= 0.7 else
-            "medium_high" if adjusted >= 0.5 else
-            "medium" if adjusted >= 0.3 else
-            "medium_low" if adjusted >= 0.2 else
-            "low"
-        )
         result.append(GridRisk(
             grid_id=g["grid_id"],
             latitude=g.get("latitude", 0),
             longitude=g.get("longitude", 0),
             risk_value=round(adjusted, 4),
-            risk_level=risk_level
+            risk_level=risk_value_to_level(adjusted)
         ))
 
     return RiskMapResponse(