Add character aliases/identity links, move-beats, keyboard help overlay

- Characters can carry aliases and be linked as the same underlying
  person (canonical SameCharacterAsId, optional reveal chapter/note),
  surfaced through the API, MCP tools, agent toolset, and web UI.
- Characters page redesigned as a filterable/sortable table (name+
  aliases, role, importance, occupation, tags) instead of a sidebar
  list, to stay usable as the cast grows.
- Beats can be moved between chapters (BeatService.MoveAsync + MCP/
  agent tool + endpoint).
- Add a keyboard-shortcuts help overlay (HelpButton/HelpOverlayContext)
  wired into the project layout.
- CLAUDE.md: require every frontend component to carry a unique id
  attribute; apply it to CharacterMultiSelect and MarkdownEditor.

src/Novelly.Mcp/Tools/BeatTools.cs

@@ -78,4 +78,15 @@ public static class BeatTools
         [Description("Beat ids in their new order.")] Guid[] beatIds,
         CancellationToken ct) =>
         api.PostAsync($"/api/chapters/{chapterId}/beats/reorder", new { beatIds }, ct);
+
+    [McpServerTool(Name = "move_beats")]
+    [Description("Move one or more beats from one chapter to another, appending them to the "
+                 + "target chapter's end in the order given.")]
+    public static Task<CallToolResult> MoveBeats(
+        NovelApiClient api,
+        [Description("The beats' current chapter id.")] Guid chapterId,
+        [Description("Id of the chapter to move the beats into.")] Guid targetChapterId,
+        [Description("Ids of the beats to move.")] Guid[] beatIds,
+        CancellationToken ct) =>
+        api.PostAsync($"/api/chapters/{chapterId}/beats/move", new { targetChapterId, beatIds }, ct);
 }