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/.

CLAUDE.md

@@ -47,6 +47,8 @@ Serilog console via `AddSerilog` (not `UseSerilog` — keeps OTel provider for A
 
 # Coding
 
+- No comments — no `///` XML doc, no `//` line comments, no `/* */` blocks, in C#, TS, or CSS. Unclear code → rename for
+  clarity or extract a well-named method instead of explaining it.
 - Descriptive names all classes/methods. No generic: Provider, Manager, Helper
 - Match formatting/style from `.editorconfig`
 - Wrap lines at 220 chars, single line if fewer