Add outline import feature; drop Dto naming, map entities at the API boundary

Services now return entities; endpoints (and the agent toolsets) map to
*Response records instead of services building wire DTOs themselves.
Also brings in the outline-import agent, MCP tool, ledger and web dialog
that were already in progress on disk.

src/Novelly.Api/Chapters/ChapterContracts.cs

@@ -0,0 +1,150 @@
+using Novelly.Api.Beats;
+using Novelly.Api.Common;
+using Novelly.Api.Common.Validation;
+using Novelly.Api.Scenes;
+using Novelly.Api.Tags;
+
+namespace Novelly.Api.Chapters;
+
+public record ChapterSummaryResponse(
+    Guid Id,
+    Guid ProjectId,
+    int Number,
+    string Title,
+    string? Summary,
+    Guid? PovCharacterId,
+    string? PovCharacterName,
+    string? Setting,
+    DraftStatus Status,
+    int? TargetWordCount,
+    int BeatCount,
+    int SceneCount,
+    int WordCount,
+    IReadOnlyList<TagResponse> Tags);
+
+/// <summary>
+/// A chapter in full: the outline (a paragraph of summary plus an ordered beat table)
+/// and the prose layer (scenes).
+/// </summary>
+public record ChapterResponse(
+    Guid Id,
+    Guid ProjectId,
+    int Number,
+    string Title,
+    string? Summary,
+    Guid? PovCharacterId,
+    string? PovCharacterName,
+    string? Setting,
+    string? Notes,
+    DraftStatus Status,
+    int? TargetWordCount,
+    IReadOnlyList<BeatResponse> Beats,
+    IReadOnlyList<SceneResponse> Scenes,
+    IReadOnlyList<TagResponse> Tags,
+    DateTimeOffset UpdatedAt);
+
+public record CreateChapterRequest(
+    string Title,
+    int? Number = null,
+    string? Summary = null,
+    Guid? PovCharacterId = null,
+    string? Setting = null,
+    string? Notes = null,
+    DraftStatus Status = DraftStatus.Planned,
+    int? TargetWordCount = null,
+    IReadOnlyList<string>? Tags = null);
+
+public class CreateChapterRequestValidator : IModelValidator<CreateChapterRequest>
+{
+    public ValidationResult Validate(CreateChapterRequest model)
+    {
+        var result = new ValidationResult();
+
+        if (string.IsNullOrWhiteSpace(model.Title))
+            result.AddError("Title", "'Title' must not be empty.");
+        else if (model.Title.Length > 200)
+            result.AddError("Title", "'Title' must be 200 characters or fewer.");
+
+        ChapterValidation.OptionalFields(model.Number, model.Summary, model.Setting, model.Notes, model.TargetWordCount, model.Tags, result);
+
+        return result;
+    }
+}
+
+/// <summary>
+/// Patch-style update. A null field is left alone; an empty string clears it. Passing a
+/// <see cref="Tags"/> list replaces the chapter's tags outright.
+/// </summary>
+public record UpdateChapterRequest(
+    string? Title = null,
+    int? Number = null,
+    string? Summary = null,
+    Guid? PovCharacterId = null,
+    string? Setting = null,
+    string? Notes = null,
+    DraftStatus? Status = null,
+    int? TargetWordCount = null,
+    IReadOnlyList<string>? Tags = null);
+
+public class UpdateChapterRequestValidator : IModelValidator<UpdateChapterRequest>
+{
+    public ValidationResult Validate(UpdateChapterRequest model)
+    {
+        var result = new ValidationResult();
+
+        if (model.Title is not null)
+        {
+            if (model.Title.Length == 0)
+                result.AddError("Title", "'Title' can not be cleared — a chapter always needs one.");
+            else if (model.Title.Length > 200)
+                result.AddError("Title", "'Title' must be 200 characters or fewer.");
+        }
+
+        ChapterValidation.OptionalFields(model.Number, model.Summary, model.Setting, model.Notes, model.TargetWordCount, model.Tags, result);
+
+        return result;
+    }
+}
+
+file static class ChapterValidation
+{
+    public static void OptionalFields(
+        int? number, string? summary, string? setting, string? notes, int? targetWordCount, IReadOnlyList<string>? tags, ValidationResult result)
+    {
+        if (number is <= 0)
+            result.AddError("Number", "'Number' must be greater than zero.");
+
+        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 (notes is { Length: > 20000 })
+            result.AddError("Notes", "'Notes' must be 20,000 characters or fewer.");
+
+        if (targetWordCount is < 0)
+            result.AddError("TargetWordCount", "'Target Word Count' must be zero or greater.");
+
+        if (tags is not null && tags.Any(string.IsNullOrWhiteSpace))
+            result.AddError("Tags", "'Tags' must not contain blank entries.");
+    }
+}
+
+public static class ChapterMapping
+{
+    public static ChapterResponse ToResponse(this Chapter c) => new(
+        c.Id, c.ProjectId, c.Number, c.Title, c.Summary,
+        c.PovCharacterId, c.PovCharacter?.Name, c.Setting, c.Notes,
+        c.Status, c.TargetWordCount,
+        [.. c.Beats.OrderBy(b => b.SortOrder).Select(b => b.ToResponse())],
+        [.. c.Scenes.OrderBy(s => s.SortOrder).Select(s => s.ToResponse())],
+        [.. c.Tags.OrderBy(t => t.Name).Select(t => t.ToResponse())],
+        c.UpdatedAt);
+
+    public static ChapterSummaryResponse ToSummaryResponse(this Chapter c) => new(
+        c.Id, c.ProjectId, c.Number, c.Title, c.Summary,
+        c.PovCharacterId, c.PovCharacter?.Name, c.Setting, c.Status, c.TargetWordCount,
+        c.Beats.Count, c.Scenes.Count, c.Scenes.Sum(s => s.WordCount),
+        [.. c.Tags.OrderBy(t => t.Name).Select(t => t.ToResponse())]);
+}