Add unit tests for Environments, Audit, and Webhooks namespaces (#6)

## Summary
- Add missing unit test coverage for the Environments, Audit, and Webhooks namespaces (raises them from ~0-62% to 91-100%)
- Exclude WebhookBackgroundService/WebhookRetryBackgroundService from coverage (require live DI/DB, disallowed by CLAUDE.md's no-InMemory/WebApplicationFactory rule)

## Test plan
- [x] `dotnet test` full suite passes (646/646)
- [x] Coverage report confirms Environments ~99.5%, Audit 100%, Webhooks ~91%

Reviewed-on: #6

tests/api/MicCheck.Api.Tests.Unit/Audit/AuditLogsControllerTests.cs

@@ -0,0 +1,118 @@
+using MicCheck.Api.Audit;
+using MicCheck.Api.Common;
+using MicCheck.Api.Data;
+using MicCheck.Api.Environments;
+using MicCheck.Api.Organizations;
+using MicCheck.Api.Projects;
+using MicCheck.Api.Tests.Unit.TestSupport;
+using MicCheck.Api.Users;
+using Microsoft.AspNetCore.Mvc;
+using Moq;
+using NUnit.Framework;
+using AppEnvironment = MicCheck.Api.Environments.Environment;
+
+namespace MicCheck.Api.Tests.Unit.Audit;
+
+[TestFixture]
+public class AuditLogsControllerTests
+{
+    private Mock<IMicCheckDbContext> _db = null!;
+    private List<Organization> _organizations = null!;
+    private List<Project> _projects = null!;
+    private List<AppEnvironment> _environments = null!;
+    private List<AuditLog> _auditLogs = null!;
+    private AuditLogsController _controller = null!;
+
+    private const int OrganizationId = 1;
+    private const int ProjectId = 1;
+    private const int EnvironmentId = 1;
+    private const string ApiKey = "env-key";
+
+    [SetUp]
+    public void SetUp()
+    {
+        _db = new Mock<IMicCheckDbContext>();
+
+        _organizations = [new Organization { Id = OrganizationId, Name = "Org", CreatedAt = DateTimeOffset.UtcNow }];
+        _db.SetupDbSet(c => c.Organizations, _organizations);
+
+        _projects = [new Project { Id = ProjectId, Name = "Project", OrganizationId = OrganizationId, CreatedAt = DateTimeOffset.UtcNow }];
+        _db.SetupDbSet(c => c.Projects, _projects);
+
+        _environments = [new AppEnvironment { Id = EnvironmentId, Name = "Production", ApiKey = ApiKey, ProjectId = ProjectId, CreatedAt = DateTimeOffset.UtcNow }];
+        _db.SetupDbSet(c => c.Environments, _environments);
+
+        _auditLogs = [];
+        _db.SetupDbSet(c => c.AuditLogs, _auditLogs);
+        _db.SetupDbSet(c => c.Users, []);
+
+        var auditServiceMock = new Mock<AuditService>(_db.Object, null!, new MicCheck.Api.Webhooks.WebhookQueue());
+        var auditService = auditServiceMock.Object;
+
+        _controller = new AuditLogsController(
+            new AuditLogQueryService(_db.Object),
+            new OrganizationService(_db.Object, auditService),
+            new ProjectService(_db.Object, auditService),
+            new EnvironmentService(_db.Object, auditService));
+    }
+
+    [Test]
+    public async Task WhenListingByOrganizationThatDoesNotExist_ThenNotFoundIsReturned()
+    {
+        var result = await _controller.ListByOrganization(999, new AuditLogFilter(), CancellationToken.None);
+
+        Assert.That(result.Result, Is.InstanceOf<NotFoundResult>());
+    }
+
+    [Test]
+    public async Task WhenListingByOrganizationThatExists_ThenMatchingLogsAreReturned()
+    {
+        _auditLogs.Add(new AuditLog { Id = 1, ResourceType = "Feature", ResourceId = "1", Action = "created", OrganizationId = OrganizationId, CreatedAt = DateTimeOffset.UtcNow });
+
+        var result = await _controller.ListByOrganization(OrganizationId, new AuditLogFilter(), CancellationToken.None);
+
+        var ok = result.Result as OkObjectResult;
+        var body = ok!.Value as PaginatedResponse<AuditLogResponse>;
+        Assert.That(body!.Count, Is.EqualTo(1));
+    }
+
+    [Test]
+    public async Task WhenListingByProjectThatDoesNotExist_ThenNotFoundIsReturned()
+    {
+        var result = await _controller.ListByProject(999, new AuditLogFilter(), CancellationToken.None);
+
+        Assert.That(result.Result, Is.InstanceOf<NotFoundResult>());
+    }
+
+    [Test]
+    public async Task WhenListingByProjectThatExists_ThenMatchingLogsAreReturned()
+    {
+        _auditLogs.Add(new AuditLog { Id = 1, ResourceType = "Feature", ResourceId = "1", Action = "created", OrganizationId = OrganizationId, ProjectId = ProjectId, CreatedAt = DateTimeOffset.UtcNow });
+
+        var result = await _controller.ListByProject(ProjectId, new AuditLogFilter(), CancellationToken.None);
+
+        var ok = result.Result as OkObjectResult;
+        var body = ok!.Value as PaginatedResponse<AuditLogResponse>;
+        Assert.That(body!.Count, Is.EqualTo(1));
+    }
+
+    [Test]
+    public async Task WhenListingByEnvironmentThatDoesNotExist_ThenNotFoundIsReturned()
+    {
+        var result = await _controller.ListByEnvironment("missing-key", new AuditLogFilter(), CancellationToken.None);
+
+        Assert.That(result.Result, Is.InstanceOf<NotFoundResult>());
+    }
+
+    [Test]
+    public async Task WhenListingByEnvironmentThatExists_ThenMatchingLogsAreReturned()
+    {
+        _auditLogs.Add(new AuditLog { Id = 1, ResourceType = "Feature", ResourceId = "1", Action = "created", OrganizationId = OrganizationId, EnvironmentId = EnvironmentId, CreatedAt = DateTimeOffset.UtcNow });
+
+        var result = await _controller.ListByEnvironment(ApiKey, new AuditLogFilter(), CancellationToken.None);
+
+        var ok = result.Result as OkObjectResult;
+        var body = ok!.Value as PaginatedResponse<AuditLogResponse>;
+        Assert.That(body!.Count, Is.EqualTo(1));
+    }
+}