Retrieves the state-bound values from the client's state_store and removes
the entry to enforce single-use semantics.
state_store_get_remove(client, state, shiny_session = NULL)A list with browser_token, pkce_code_verifier, and nonce.
Throws an error via err_invalid_state() if retrieval or removal fails,
or if the retrieved value is missing/malformed.
OAuthClient instance
Plain (decrypted) state string used as the logical key
Optional pre-captured Shiny session context (from
capture_shiny_session_context()) to include in audit events. Used when
calling from async workers that lack access to the reactive domain.