Remove Scenes, group beats by multiple characters; strip comments repo-wide

Drop the Scene entity/grouping in favor of chapters carrying prose directly
and beats belonging to many characters. Add markdown editor + character
multi-select components to the web client. Remove all XML doc and inline
comments across the touched C#/TS/CSS files in favor of self-documenting
names, and record that convention in CLAUDE.md. Add .mcp.json (local MCP
server config, no secrets) and ignore .idea/.

src/Novelly.Api/Chapters/ChapterEndpoints.cs

@@ -35,7 +35,7 @@ public static class ChapterEndpoints
 
         chapters.MapGet("/{id:guid}", async (Guid id, ChapterService service, CancellationToken ct) =>
                 (await service.GetAsync(id, ct))?.ToResponse().ToApiResult())
-            .WithSummary("Read a chapter with all of its scenes.");
+            .WithSummary("Read a chapter with its beats and prose.");
 
         chapters.MapPatch("/{id:guid}", async (
                 Guid id, UpdateChapterRequest request, ChapterService service, CancellationToken ct) =>
@@ -44,7 +44,7 @@ public static class ChapterEndpoints
 
         chapters.MapDelete("/{id:guid}", async (Guid id, ChapterService service, CancellationToken ct) =>
                 await service.DeleteAsync(id, ct) ? Results.NoContent() : Results.NotFound())
-            .WithSummary("Delete a chapter and its scenes.");
+            .WithSummary("Delete a chapter.");
 
         return app;
     }