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/.

tests/Novelly.Api.Tests/AnthropicClientTests.cs

@@ -10,9 +10,6 @@ public class AnthropicClientTests
 {
     [Test]
     public void Constructing_without_a_key_does_not_throw() =>
-        // The agent service takes this as a dependency and also serves read-only endpoints
-        // (listing conversations, reading a transcript). Throwing at construction would
-        // take those down on any install that has not configured a key yet.
         Assert.That(
             () => new AnthropicAgentModelClient(Options.Create(new AgentOptions()), NullLogger<AnthropicAgentModelClient>.Instance),
             Throws.Nothing);