* fix rotating kv cache for chat use case
* reorg + fixes to caching, unify prompt caching across types and use cases for e.g. caching during a chat
* nit in chat
* fix tests
* fix tests
* fix tests
* docs
* chat command
* comments + docs
* Define meta_state on all Cache implementations
* fixes + trim_prompt_cache api
* fix default model
---------
Co-authored-by: Angelos Katharopoulos <a_katharopoulos@apple.com>
