feat: real ERPNext Healthcare integration + setup tooling

- Replace all mock tools with real ERPNext Healthcare operations
- ERPNextHealthcare class: patients, practitioners, appointments, schedules
- check_availability queries real practitioner schedules from ERPNext
- create_appointment finds/creates patient + validates conflicts + books in ERPNext
- Add /api/v1/config/test endpoint to validate all service connections
- Add scripts/validate_setup.py for CLI validation of Meta/OpenAI/ERPNext/DB
- Add scripts/seed_knowledge.py with full SKEEN catalog (services, products, packages, FAQ)
- Add tests for webhook, health, and WhatsApp client
- Update main.py to include config router

tests/test_health.py

@@ -0,0 +1,24 @@
+"""Tests for health check endpoints."""
+
+from fastapi.testclient import TestClient
+
+from src.main import create_app
+
+
+class TestHealth:
+    def test_health_check(self):
+        app = create_app()
+        client = TestClient(app)
+        response = client.get("/health")
+        assert response.status_code == 200
+        data = response.json()
+        assert data["status"] == "healthy"
+        assert "timestamp" in data
+
+    def test_ready_check(self):
+        app = create_app()
+        client = TestClient(app)
+        response = client.get("/ready")
+        assert response.status_code == 200
+        data = response.json()
+        assert "database" in data