Fetches all Resource matching the given filters.

Maintains an in-memory cache using Last-Modified/If-Modified-Since headers. Always checks with the server to ensure the cached data is not stale, but since 304 responses don't count against the rate limit, this makes it practical to use anonymous access (which has a very low limit). If the server returns a 5xx error and there is a cached response, returns it and logs a warning.

Throws V3API::RequestError when an unexpected HTTP status is received, including a 5xx status when there is no cached response.