Add 'proficiency' property to subclass object

So

When you choose life domain for cleric, you get proficiency with heavy armor, but it is not specified in data itself, you just get a feature called "bonus proficiency", which itself is not too descriptive.

My suggestion is, maybe add `proficiencies` property to domain object? And add such property to aby subclass giving you proficiencies?

Look at the subclass data structure in the repository, likely in a JSON file for cleric domains. Identify where subclass objects are defined and add a 'proficiencies' property. Check existing examples of proficiency data elsewhere in the database to understand the format. Verify the change by reviewing the data consistency and possibly running any validation scripts.

Do mô hình lập chỉ mục viết ra từ nội dung của issue.