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_stuff.py

@@ -0,0 +1,162 @@
+"""Tests for python/stuff modules."""
+
+from __future__ import annotations
+
+from python.stuff.capasitor import (
+    calculate_capacitor_capacity,
+    calculate_pack_capacity,
+    calculate_pack_capacity2,
+)
+from python.stuff.voltage_drop import (
+    Length,
+    LengthUnit,
+    MaterialType,
+    Temperature,
+    TemperatureUnit,
+    calculate_awg_diameter_mm,
+    calculate_resistance_per_meter,
+    calculate_wire_area_m2,
+    get_material_resistivity,
+    max_wire_length,
+    voltage_drop,
+)
+
+
+# --- capasitor tests ---
+
+
+def test_calculate_capacitor_capacity() -> None:
+    """Test capacitor capacity calculation."""
+    result = calculate_capacitor_capacity(voltage=2.7, farads=500)
+    assert isinstance(result, float)
+
+
+def test_calculate_pack_capacity() -> None:
+    """Test pack capacity calculation."""
+    result = calculate_pack_capacity(cells=10, cell_voltage=2.7, farads=500)
+    assert isinstance(result, float)
+
+
+def test_calculate_pack_capacity2() -> None:
+    """Test pack capacity2 calculation returns capacity and cost."""
+    capacity, cost = calculate_pack_capacity2(cells=10, cell_voltage=2.7, farads=3000, cell_cost=11.60)
+    assert isinstance(capacity, float)
+    assert cost == 11.60 * 10
+
+
+# --- voltage_drop tests ---
+
+
+def test_temperature_celsius() -> None:
+    """Test Temperature with celsius."""
+    t = Temperature(20.0, TemperatureUnit.CELSIUS)
+    assert float(t) == 20.0
+
+
+def test_temperature_fahrenheit() -> None:
+    """Test Temperature with fahrenheit."""
+    t = Temperature(100.0, TemperatureUnit.FAHRENHEIT)
+    assert isinstance(float(t), float)
+
+
+def test_temperature_kelvin() -> None:
+    """Test Temperature with kelvin."""
+    t = Temperature(300.0, TemperatureUnit.KELVIN)
+    assert isinstance(float(t), float)
+
+
+def test_temperature_default_unit() -> None:
+    """Test Temperature defaults to celsius."""
+    t = Temperature(25.0)
+    assert float(t) == 25.0
+
+
+def test_length_meters() -> None:
+    """Test Length in meters."""
+    length = Length(10.0, LengthUnit.METERS)
+    assert float(length) == 10.0
+
+
+def test_length_feet() -> None:
+    """Test Length in feet."""
+    length = Length(10.0, LengthUnit.FEET)
+    assert abs(float(length) - 3.048) < 0.001
+
+
+def test_length_inches() -> None:
+    """Test Length in inches."""
+    length = Length(100.0, LengthUnit.INCHES)
+    assert abs(float(length) - 2.54) < 0.001
+
+
+def test_length_feet_method() -> None:
+    """Test Length.feet() conversion."""
+    length = Length(1.0, LengthUnit.METERS)
+    assert abs(length.feet() - 3.2808) < 0.001
+
+
+def test_get_material_resistivity_default_temp() -> None:
+    """Test material resistivity with default temperature."""
+    r = get_material_resistivity(MaterialType.COPPER)
+    assert r > 0
+
+
+def test_get_material_resistivity_with_temp() -> None:
+    """Test material resistivity with explicit temperature."""
+    r = get_material_resistivity(MaterialType.ALUMINUM, Temperature(50.0))
+    assert r > 0
+
+
+def test_get_material_resistivity_all_materials() -> None:
+    """Test resistivity for all materials."""
+    for material in MaterialType:
+        r = get_material_resistivity(material)
+        assert r > 0
+
+
+def test_calculate_awg_diameter_mm() -> None:
+    """Test AWG diameter calculation."""
+    d = calculate_awg_diameter_mm(10)
+    assert d > 0
+
+
+def test_calculate_wire_area_m2() -> None:
+    """Test wire area calculation."""
+    area = calculate_wire_area_m2(10)
+    assert area > 0
+
+
+def test_calculate_resistance_per_meter() -> None:
+    """Test resistance per meter calculation."""
+    r = calculate_resistance_per_meter(10)
+    assert r > 0
+
+
+def test_voltage_drop_calculation() -> None:
+    """Test voltage drop calculation."""
+    vd = voltage_drop(
+        gauge=10,
+        material=MaterialType.CCA,
+        length=Length(20, LengthUnit.FEET),
+        current_a=20,
+    )
+    assert vd > 0
+
+
+def test_max_wire_length_default_temp() -> None:
+    """Test max wire length with default temperature."""
+    result = max_wire_length(gauge=10, material=MaterialType.CCA, current_amps=20)
+    assert float(result) > 0
+    assert result.feet() > 0
+
+
+def test_max_wire_length_with_temp() -> None:
+    """Test max wire length with explicit temperature."""
+    result = max_wire_length(
+        gauge=10,
+        material=MaterialType.COPPER,
+        current_amps=10,
+        voltage_drop=0.5,
+        temperature=Temperature(30.0),
+    )
+    assert float(result) > 0