NewCommandHandler creates a new command handler for feed commands.

DefaultSet is a provider set for creating a command handler and its dependencies.

CommandHandler processes feed-related commands and updates the data store appropriately.

ImportPostsCommand is a request to import posts that were scraped from a feed into the database.

RefreshCommand is a request to refresh a feed's contents and create/update posts for the feed.

SubscribeCommand is a request to subscribe a user to a feed by URL.

UnsubscribeCommand is a request to unsubscribe a user from a feed.