release: v1.6.1 - Weather forecasts, sun times, air quality

- Weather fetch now returns 7-day forecasts with UV index
- New /volatile/fetch/sun/{city} endpoint for sunrise/sunset
- New /volatile/fetch/air_quality/{city} endpoint for AQI and pollutants
- OpenMeteoProvider now implements AirQualityProvider interface

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

tests/test_volatile.py

@@ -110,7 +110,7 @@ class TestVolatileNamespaces:
 
     def test_namespace_count(self):
         """Test we have the expected number of namespaces."""
-        assert len(VolatileNamespace) == 11
+        assert len(VolatileNamespace) == 12  # Including SUN for sunrise/sunset
 
 
 class TestVolatileListResponse: