Replace chapter setting with multi-select locations; add chapter character summary

Chapters now carry many Locations (new Tags-style entity with cross-referencing)
instead of a single free-text Setting field, with a Locations tab on the novel
for browsing them and seeing every chapter set at each one. Also surfaces the
distinct characters appearing in a chapter's beats, linked, under the beat/word
count on the outline tab.

src/Novelly.Mcp/Tools/ManuscriptTools.cs

@@ -32,7 +32,7 @@ public static class ManuscriptTools
         CancellationToken ct,
         [Description("Position in the manuscript, 1-based.")] int? number = null,
         [Description("The chapter's outline summary paragraph.")] string? summary = null,
-        [Description("Where and when the chapter takes place.")] string? setting = null,
+        [Description("Where and when the chapter takes place. Unknown locations are created.")] string[]? locations = null,
         [Description("Planned, Outlined, Drafted, Revised or Final.")] string? status = null,
         [Description("Target length in words.")] int? targetWordCount = null,
         [Description("The chapter's drafted text, in markdown, if you are writing it now.")] string? prose = null,
@@ -42,7 +42,7 @@ public static class ManuscriptTools
             title,
             number,
             summary,
-            setting,
+            locations,
             status = status ?? "Planned",
             targetWordCount,
             prose,
@@ -50,7 +50,7 @@ public static class ManuscriptTools
         }, ct);
 
     [McpServerTool(Name = "update_chapter")]
-    [Description("Revise a chapter's title, number, summary, setting, notes, status "
+    [Description("Revise a chapter's title, number, summary, locations, notes, status "
                  + "or drafted prose. Use 'prose' to write or replace the chapter's draft text in "
                  + "markdown; the word count is recomputed automatically.")]
     public static Task<CallToolResult> UpdateChapter(
@@ -60,12 +60,12 @@ public static class ManuscriptTools
         [Description("New title.")] string? title = null,
         [Description("Position in the manuscript.")] int? number = null,
         [Description("The chapter's outline summary paragraph.")] string? summary = null,
-        [Description("Where and when the chapter takes place.")] string? setting = null,
+        [Description("Where and when the chapter takes place. Replaces the existing locations. Unknown locations are created.")] string[]? locations = null,
         [Description("Anything else worth recording.")] string? notes = null,
         [Description("Planned, Outlined, Drafted, Revised or Final.")] string? status = null,
         [Description("Target length in words.")] int? targetWordCount = null,
         [Description("The chapter's drafted text, in markdown.")] string? prose = null,
         [Description("Tags for cross-referencing. Replaces the existing tags.")] string[]? tags = null) =>
         api.PatchAsync($"/api/chapters/{chapterId}",
-            new { title, number, summary, setting, notes, status, targetWordCount, prose, tags }, ct);
+            new { title, number, summary, locations, notes, status, targetWordCount, prose, tags }, ct);
 }