Rename Project concept to Novel across the stack

Renames the domain concept from Project to Novel throughout the backend
(entities, DTOs, services, endpoints, ProjectAccessService/Permission,
ProjectId foreign keys), MCP server (tool names and routes), and the
React/Vite frontend (types, hooks, routes, components). Adds a new EF
Core migration (RenameProjectToNovel) using RenameTable/RenameColumn to
preserve existing data instead of dropping/recreating tables. Updates
CLAUDE.md's structure section to reference Novels/ instead of Projects/.

src/Novelly.Api/Users/NovelMemberContracts.cs

@@ -0,0 +1,23 @@
+using Novelly.Api.Common.Validation;
+
+namespace Novelly.Api.Users;
+
+public record GrantAccessRequest(string Email, NovelRole NovelRole);
+
+public record NovelMemberResponse(Guid UserId, string Email, string DisplayName, NovelRole NovelRole, DateTimeOffset GrantedAt);
+
+public class GrantAccessRequestValidator : IModelValidator<GrantAccessRequest>
+{
+    public ValidationResult Validate(GrantAccessRequest model)
+    {
+        var result = new ValidationResult();
+        result.AddRequiredTextErrors("Email", "Email", model.Email, 256);
+        return result;
+    }
+}
+
+public static class NovelMemberMapping
+{
+    public static NovelMemberResponse ToResponse(this NovelMember m) =>
+        new(m.UserId, m.User!.Email ?? string.Empty, m.User.DisplayName, m.NovelRole, m.GrantedAt);
+}