Add unit tests for 9 new services/controllers and expand existing test coverage

116 tests passing: JobPhotoService, MeasurementConversionService, PlatformSettingsService,
QuoteApprovalController, QuotePhotoService, ShopCapabilityCalculator, StorageMigrationService,
TenantContext, UsageQuotaController — plus expanded PricingCalculation, Registration, and
Subscription tests.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/PowderCoating.UnitTests/MeasurementConversionServiceTests.cs

@@ -0,0 +1,62 @@
+using PowderCoating.Application.Services;
+
+namespace PowderCoating.UnitTests;
+
+public class MeasurementConversionServiceTests
+{
+    private readonly MeasurementConversionService _service = new();
+
+    [Fact]
+    public void SquareFeetToMeters_AndBack_RoundTripsToCurrencyStylePrecision()
+    {
+        var squareMeters = _service.SquareFeetToMeters(100m);
+        var squareFeet = _service.SquareMetersToFeet(squareMeters);
+
+        Assert.Equal(9.29m, squareMeters);
+        Assert.Equal(100m, squareFeet, 1);
+    }
+
+    [Fact]
+    public void PoundsToKilograms_AndBack_RoundTripsToCurrencyStylePrecision()
+    {
+        var kilograms = _service.PoundsToKilograms(10m);
+        var pounds = _service.KilogramsToPounds(kilograms);
+
+        Assert.Equal(4.54m, kilograms);
+        Assert.Equal(10.01m, pounds, 2);
+    }
+
+    [Fact]
+    public void ConvertArea_WhenImperialToMetric_UsesSquareFeetConversion()
+    {
+        var result = _service.ConvertArea(50m, fromImperial: true, toMetric: true);
+
+        Assert.Equal(4.65m, result);
+    }
+
+    [Fact]
+    public void ConvertArea_WhenSourceAndTargetAreSameSystem_ReturnsOriginalValue()
+    {
+        Assert.Equal(12.34m, _service.ConvertArea(12.34m, fromImperial: true, toMetric: false));
+        Assert.Equal(56.78m, _service.ConvertArea(56.78m, fromImperial: false, toMetric: true));
+    }
+
+    [Fact]
+    public void ConvertWeight_WhenMetricToImperial_UsesKilogramsToPounds()
+    {
+        var result = _service.ConvertWeight(5m, fromImperial: false, toMetric: false);
+
+        Assert.Equal(11.02m, result);
+    }
+
+    [Fact]
+    public void UnitLabelHelpers_ReturnExpectedMetricAndImperialLabels()
+    {
+        Assert.Equal("sq ft", _service.GetAreaUnitLabel(false));
+        Assert.Equal("sq m", _service.GetAreaUnitLabel(true));
+        Assert.Equal("lb", _service.GetWeightUnitLabel(false));
+        Assert.Equal("kg", _service.GetWeightUnitLabel(true));
+        Assert.Equal("sq ft/lb", _service.GetCoverageUnitLabel(false));
+        Assert.Equal("sq m/kg", _service.GetCoverageUnitLabel(true));
+    }
+}