oauth_chopper

Add and configure OAuth2 authentication for a Chopper HTTP client using `oauth_chopper`. Use when asked to "add OAuth to Chopper", "setup oauth_chopper", "integrate OAuth2 with Chopper", "add authentication to my API client", or when setting up any of the supported grant types (resource owner password, client credentials, authorization code).

Implement persistent token storage for `oauth_chopper` by creating a custom `OAuthStorage` class. Use when asked to "persist OAuth tokens", "save OAuth credentials", "implement OAuthStorage", "store tokens securely", or "oauth_chopper storage".