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.Api/Chapters/ChapterContracts.cs

@@ -1,6 +1,7 @@
 using Novelly.Api.Beats;
 using Novelly.Api.Common;
 using Novelly.Api.Common.Validation;
+using Novelly.Api.Locations;
 using Novelly.Api.Tags;
 
 namespace Novelly.Api.Chapters;
@@ -11,7 +12,7 @@ public record ChapterSummaryResponse(
     int Number,
     string Title,
     string? Summary,
-    string? Setting,
+    IReadOnlyList<LocationResponse> Locations,
     DraftStatus Status,
     int? TargetWordCount,
     int BeatCount,
@@ -25,7 +26,7 @@ public record ChapterResponse(
     int Number,
     string Title,
     string? Summary,
-    string? Setting,
+    IReadOnlyList<LocationResponse> Locations,
     string? Notes,
     DraftStatus Status,
     int? TargetWordCount,
@@ -39,7 +40,7 @@ public record CreateChapterRequest(
     string Title,
     int? Number = null,
     string? Summary = null,
-    string? Setting = null,
+    IReadOnlyList<string>? Locations = null,
     string? Notes = null,
     DraftStatus Status = DraftStatus.Planned,
     int? TargetWordCount = null,
@@ -53,7 +54,7 @@ public class CreateChapterRequestValidator : IModelValidator<CreateChapterReques
         var result = new ValidationResult();
 
         result.AddRequiredTextErrors("Title", "Title", model.Title, 200);
-        ChapterValidation.OptionalFields(model.Number, model.Summary, model.Setting, model.Notes, model.TargetWordCount, model.Prose, model.Tags, result);
+        ChapterValidation.OptionalFields(model.Number, model.Summary, model.Locations, model.Notes, model.TargetWordCount, model.Prose, model.Tags, result);
 
         return result;
     }
@@ -63,7 +64,7 @@ public record UpdateChapterRequest(
     string? Title = null,
     int? Number = null,
     string? Summary = null,
-    string? Setting = null,
+    IReadOnlyList<string>? Locations = null,
     string? Notes = null,
     DraftStatus? Status = null,
     int? TargetWordCount = null,
@@ -77,7 +78,7 @@ public class UpdateChapterRequestValidator : IModelValidator<UpdateChapterReques
         var result = new ValidationResult();
 
         result.AddUnclearableTextErrors("Title", "Title", model.Title, "a chapter", 200);
-        ChapterValidation.OptionalFields(model.Number, model.Summary, model.Setting, model.Notes, model.TargetWordCount, model.Prose, model.Tags, result);
+        ChapterValidation.OptionalFields(model.Number, model.Summary, model.Locations, model.Notes, model.TargetWordCount, model.Prose, model.Tags, result);
 
         return result;
     }
@@ -86,7 +87,7 @@ public class UpdateChapterRequestValidator : IModelValidator<UpdateChapterReques
 file static class ChapterValidation
 {
     public static void OptionalFields(
-        int? number, string? summary, string? setting, string? notes, int? targetWordCount, string? prose,
+        int? number, string? summary, IReadOnlyList<string>? locations, string? notes, int? targetWordCount, string? prose,
         IReadOnlyList<string>? tags, ValidationResult result)
     {
         if (number is <= 0)
@@ -95,8 +96,8 @@ file static class ChapterValidation
         if (summary is { Length: > 20000 })
             result.AddError("Summary", "'Summary' must be 20,000 characters or fewer.");
 
-        if (setting is { Length: > 500 })
-            result.AddError("Setting", "'Setting' must be 500 characters or fewer.");
+        if (locations is not null && locations.Any(string.IsNullOrWhiteSpace))
+            result.AddError("Locations", "'Locations' must not contain blank entries.");
 
         if (notes is { Length: > 20000 })
             result.AddError("Notes", "'Notes' must be 20,000 characters or fewer.");
@@ -116,7 +117,8 @@ public static class ChapterMapping
 {
     public static ChapterResponse ToResponse(this Chapter c) => new(
         c.Id, c.NovelId, c.Number, c.Title, c.Summary,
-        c.Setting, c.Notes,
+        [.. c.Locations.OrderBy(l => l.Name).Select(l => l.ToResponse())],
+        c.Notes,
         c.Status, c.TargetWordCount,
         [.. c.Beats.OrderBy(b => b.SortOrder).Select(b => b.ToResponse())],
         c.Prose, c.WordCount,
@@ -125,7 +127,8 @@ public static class ChapterMapping
 
     public static ChapterSummaryResponse ToSummaryResponse(this Chapter c) => new(
         c.Id, c.NovelId, c.Number, c.Title, c.Summary,
-        c.Setting, c.Status, c.TargetWordCount,
+        [.. c.Locations.OrderBy(l => l.Name).Select(l => l.ToResponse())],
+        c.Status, c.TargetWordCount,
         c.Beats.Count, c.WordCount,
         [.. c.Tags.OrderBy(t => t.Name).Select(t => t.ToResponse())],
         c.UpdatedAt);