Add comprehensive test suite achieving 99% code coverage

Added 35 test files with 502 tests covering all Python modules including
API routes, ORM models, splendor game logic/TUI, heater controller,
weather service, NixOS installer, ZFS dataset management, and utilities.
Coverage improved from 11% to 99% (2540/2564 statements covered).

https://claude.ai/code/session_01SVzgLDUS1Cdc4eh1ijETTh

tests/test_van_weather_main.py

@@ -0,0 +1,28 @@
+"""Tests for van_weather/main.py main() function."""
+
+from __future__ import annotations
+
+from unittest.mock import MagicMock, patch
+
+from python.van_weather.main import main
+
+
+def test_van_weather_main() -> None:
+    """Test main sets up scheduler."""
+    with (
+        patch("python.van_weather.main.BlockingScheduler") as mock_sched_cls,
+        patch("python.van_weather.main.configure_logger"),
+    ):
+        mock_sched = MagicMock()
+        mock_sched_cls.return_value = mock_sched
+
+        main(
+            ha_url="http://ha.local",
+            ha_token="token",
+            api_key="key",
+            interval=60,
+            log_level="INFO",
+        )
+
+        mock_sched.add_job.assert_called_once()
+        mock_sched.start.assert_called_once()