Introduce local fallback for book creation and improve error handling

- Added support for creating books locally when the cloud limit is reached.
- Enhanced error handling in `AddNewBookForm` with `ApiError` and fallback logic for local book creation.
- Implemented `BookTypeLimit` to manage type-specific book limits with visual indicators in `BookList`.
- Refactored `TombstoneRecord` to standardize naming conventions for better API compatibility.
- Updated `useSyncSeries` and `useSyncBooks` to handle empty tombstones gracefully.
- Updated locales with new translations for fallback and error messaging.

lib/api/client.ts

@@ -13,10 +13,20 @@ interface ApiRequestConfig {
     contentType?: ContentType;
 }
 
+export class ApiError extends Error {
+    statusCode: number;
+    constructor(message: string, statusCode: number) {
+        super(message);
+        this.statusCode = statusCode;
+        this.name = 'ApiError';
+    }
+}
+
 function handleApiError(error: unknown): never {
     if (axios.isAxiosError(error)) {
         const serverMessage: string = error.response?.data?.message || error.response?.data || error.message;
-        throw new Error(serverMessage);
+        const statusCode: number = error.response?.status ?? 500;
+        throw new ApiError(serverMessage, statusCode);
     } else if (error instanceof Error) {
         throw new Error(error.message);
     }