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/Characters/Character.cs

@@ -2,7 +2,7 @@ using Microsoft.EntityFrameworkCore;
 using Microsoft.EntityFrameworkCore.Metadata.Builders;
 using Novelly.Api.Beats;
 using Novelly.Api.Chapters;
-using Novelly.Api.Projects;
+using Novelly.Api.Novels;
 using Novelly.Api.Tags;
 
 namespace Novelly.Api.Characters;
@@ -10,8 +10,8 @@ namespace Novelly.Api.Characters;
 public class Character
 {
     public Guid Id { get; set; } = Guid.NewGuid();
-    public Guid ProjectId { get; set; }
-    public Project? Project { get; set; }
+    public Guid NovelId { get; set; }
+    public Novel? Novel { get; set; }
 
     public string Name { get; set; } = string.Empty;
     public CharacterRole Role { get; set; } = CharacterRole.Supporting;
@@ -82,7 +82,7 @@ public class CharacterEntityTypeConfiguration : IEntityTypeConfiguration<Charact
         entity.Property(c => c.Name).IsRequired().HasMaxLength(200);
         entity.Property(c => c.Role).HasConversion<string>().HasMaxLength(32);
         entity.Property(c => c.Importance).HasConversion<string>().HasMaxLength(32);
-        entity.HasIndex(c => c.ProjectId);
+        entity.HasIndex(c => c.NovelId);
         entity.HasIndex(c => c.SameCharacterAsId);
 
         entity.HasMany(c => c.Relationships).WithOne(r => r.Character!)