Adds the std crate on top of the core runtime: Supervisor with RestartPolicy
(Permanent/Transient/Temporary) and SupervisorStrategy (OneForOne/OneForAll/
RestForOne), Router with RoutingStrategy, name/monitor/group registries, StdExtension,
and Ctx/Runtime extension traits. Also extends core (worker, actor, delivery identity
hashing, config, stats), adds a fuzz target, a proptest suite, expands runtime_api
tests, and adds cfuzz cycle notes + benchmarks.
Signed-off-by: Zachery Aaron Shores-Chmielewski <zacheryasc@gmail.com>
