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/tests/conftest.py

@@ -0,0 +1,31 @@
+"""Test configuration - set env before importing app."""
+import os
+
+os.environ.setdefault("POSTGRES_USER", "test_user")
+os.environ.setdefault("POSTGRES_PASSWORD", "test_pass")
+os.environ.setdefault("POSTGRES_DB", "test_db")
+os.environ.setdefault("AUTH_SECRET_KEY", "test-secret-key")
+os.environ.setdefault("AUTH_DEFAULT_USER", "admin")
+os.environ.setdefault("AUTH_DEFAULT_PASSWORD", "admin123")
+
+import pytest
+from fastapi.testclient import TestClient
+
+
+@pytest.fixture
+def client():
+    from main import app
+    with TestClient(app) as c:
+        yield c
+
+
+@pytest.fixture
+def auth_token(client):
+    resp = client.post("/api/auth/login", json={"username": "admin", "password": "admin123"})
+    return resp.json()["access_token"]
+
+
+@pytest.fixture
+def auth_client(client, auth_token):
+    client.headers["Authorization"] = f"Bearer {auth_token}"
+    return client