db.accounts:
{
    _id: ID
    username: String,
    password: String,
    email: String,
    tag_enum: [String],
    folders: [
        {
            id: Int,
            name: String,
            bookmarks: [
                {
                    name: String,
                    url: String,
                    favicon: ???,
                    description: String,
                    tags: [Int],
                },
            ],
            subfolders: [
                ... same as in folders ...
            ]
        },
    ]
}