Save appearance settings on server

- app theme
- theme mode
- pure black mode
- manga grid item width

src/modules/metadata/services/MetadataMigrations.ts

@@ -83,7 +83,10 @@ const applyMetadataValueMigration = (meta: Metadata, migration: IMetadataMigrati
 
     metadataValueChanges.forEach(({ key, oldValue, newValue }) => {
         const migrateValue = (metaKey: string) => {
-            if (meta[metaKey].match(oldValue)) {
+            if (
+                (oldValue === undefined && meta[metaKey] === oldValue) ||
+                (oldValue !== undefined && meta[metaKey].match(oldValue))
+            ) {
                 migratedMetadata[metaKey] = typeof newValue === 'function' ? newValue(meta[metaKey]) : newValue;
             }
         };