Add outline import feature; drop Dto naming, map entities at the API boundary

Services now return entities; endpoints (and the agent toolsets) map to
*Response records instead of services building wire DTOs themselves.
Also brings in the outline-import agent, MCP tool, ledger and web dialog
that were already in progress on disk.

tests/Novelly.Api.Tests/BeatServiceTests.cs

@@ -91,8 +91,8 @@ public class BeatServiceTests : ServiceTestFixture
 
         Assert.Multiple(() =>
         {
-            Assert.That(beat.CharacterName, Is.EqualTo("Ines"));
-            Assert.That(beat.SceneTitle, Is.EqualTo("The dock at dawn"));
+            Assert.That(beat.Character!.Name, Is.EqualTo("Ines"));
+            Assert.That(beat.Scene!.Title, Is.EqualTo("The dock at dawn"));
             Assert.That(beat.WhatHappened, Does.Contain("faster than she expected"));
         });
     }
@@ -164,4 +164,25 @@ public class BeatServiceTests : ServiceTestFixture
             Assert.That(cleared.WhatHappened, Is.EqualTo("Behind the lining of the case."));
         });
     }
+
+    [Test]
+    public async Task ClearCharacter_and_ClearScene_detach_the_reference_since_a_null_id_means_leave_it_alone()
+    {
+        var ines = await Characters.CreateAsync(_projectId, new CreateCharacterRequest("Ines"));
+        var scene = await Scenes.CreateAsync(_chapterId, new CreateSceneRequest("The dock at dawn"));
+        var beat = await Beats.CreateAsync(_chapterId, new CreateBeatRequest(
+            "She burns the atlas", CharacterId: ines.Id, SceneId: scene.Id));
+
+        var untouched = (await Beats.UpdateAsync(beat.Id, new UpdateBeatRequest(Title: "She burns it")))!;
+        Assert.That(untouched.Character!.Name, Is.EqualTo("Ines"));
+
+        var cleared = (await Beats.UpdateAsync(
+            beat.Id, new UpdateBeatRequest(ClearCharacter: true, ClearScene: true)))!;
+
+        Assert.Multiple(() =>
+        {
+            Assert.That(cleared.Character, Is.Null);
+            Assert.That(cleared.Scene, Is.Null);
+        });
+    }
 }