Validate solar panel inputs and add tests

tests/test_energy_simulator.py

@@ -0,0 +1,22 @@
+import pathlib
+import sys
+
+import pytest
+
+sys.path.insert(0, str(pathlib.Path(__file__).resolve().parents[1]))
+from native_ai_quantum_energy.energy_simulator import solar_panel_output
+
+
+def test_solar_panel_output_valid():
+    energy = solar_panel_output(100, 2, 0.5)
+    assert energy == pytest.approx(100 * 0.5 * 2 * 3600)
+
+
+def test_solar_panel_output_negative_power():
+    with pytest.raises(ValueError):
+        solar_panel_output(-10, 1)
+
+
+def test_solar_panel_output_negative_hours():
+    with pytest.raises(ValueError):
+        solar_panel_output(10, -1)