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/locales/en.json

@@ -718,7 +718,10 @@
       "titleTooShort": "Title is too short. Minimum 2 characters required.",
       "titleTooLong": "Title is too long. Maximum 50 characters allowed.",
       "typeMissing": "Select a genre.",
-      "addingBook": "An error occurred while adding the book."
+      "addingBook": "An error occurred while adding the book.",
+      "limitReached": "You have reached the book limit for this type on the cloud.",
+      "saveLocally": "Save locally",
+      "localFallbackDescription": "You can still save this book locally on your device."
     },
     "bookTypeHint": {
       "title": "Type of work",

lib/locales/fr.json

@@ -717,7 +717,10 @@
       "titleTooShort": "Le titre est trop court. Minimum 2 caractères requis",
       "titleTooLong": "Le titre est trop long. Maximum 50 caractères autorisés",
       "typeMissing": "Sélectionner un genre.",
-      "addingBook": "Une erreur est survenue lors de l'ajout du livre."
+      "addingBook": "Une erreur est survenue lors de l'ajout du livre.",
+      "limitReached": "Vous avez atteint la limite de livres pour ce type sur le cloud.",
+      "saveLocally": "Sauvegarder localement",
+      "localFallbackDescription": "Vous pouvez tout de même enregistrer ce livre localement sur votre appareil."
     },
     "bookTypeHint": {
       "title": "Type d'oeuvre",