Add genre feature; extract ConfirmModal for reusable confirm dialogs

Genres seed on boot, are editable per project, and gate agent config
errors more gracefully. ConfirmModal replaces ad-hoc confirm prompts
across chapters, tags, and characters pages.

tests/Novelly.Api.Tests/GenreServiceTests.cs

@@ -0,0 +1,44 @@
+using Novelly.Api.Projects;
+
+namespace Novelly.Api.Tests;
+
+[TestFixture]
+public class GenreServiceTests : ServiceTestFixture
+{
+    [Test]
+    public async Task The_genre_list_arrives_seeded_and_alphabetical()
+    {
+        var listed = await Genres.ListAsync();
+
+        Assert.Multiple(() =>
+        {
+            Assert.That(listed, Is.Not.Empty);
+            Assert.That(listed.Select(g => g.Name), Has.Member("Fantasy").And.Member("Literary Fiction"));
+            Assert.That(listed.Select(g => g.Name), Is.Ordered);
+            Assert.That(listed.Select(g => g.Id), Is.Unique);
+        });
+    }
+
+    [Test]
+    public async Task A_project_can_be_filed_under_a_genre_off_the_list()
+    {
+        var fantasy = (await Genres.ListAsync()).First(g => g.Name == "Fantasy");
+
+        var project = await Projects.CreateAsync(new CreateProjectRequest("The Salt Road", Genre: fantasy.Name));
+
+        Assert.That(project.Genre, Is.EqualTo("Fantasy"));
+    }
+
+    [Test]
+    public async Task A_project_can_still_carry_a_genre_that_is_not_on_the_list()
+    {
+        var project = await Projects.CreateAsync(
+            new CreateProjectRequest("The Salt Road", Genre: "Nautical Gothic"));
+
+        Assert.Multiple(async () =>
+        {
+            Assert.That(project.Genre, Is.EqualTo("Nautical Gothic"));
+            Assert.That((await Genres.ListAsync()).Select(g => g.Name), Has.No.Member("Nautical Gothic"));
+        });
+    }
+}