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/Imports/ImportContracts.cs

@@ -5,7 +5,7 @@ namespace Novelly.Api.Imports;
 public record ImportJobResponse(
     Guid Id,
     string SourceRoot,
-    Guid? ProjectId,
+    Guid? NovelId,
     ImportJobStatus Status,
     string? StatusMessage,
     int ChaptersCompleted,
@@ -22,7 +22,7 @@ public enum ImportReadiness
 
 public record ImportInspectionResponse(
     ImportReadiness Readiness,
-    Guid? ProjectId,
+    Guid? NovelId,
     int ChaptersCompleted,
     int ChaptersTotal,
     IReadOnlyList<string> CompletedPasses);
@@ -62,7 +62,7 @@ public static class ImportMapping
     public static ImportJobResponse ToResponse(this ImportJob job) => new(
         job.Id,
         job.SourceRoot,
-        job.ProjectId,
+        job.NovelId,
         job.Status,
         job.StatusMessage,
         job.ChaptersCompleted,