Summary:
* add openssh-client to the builder image and mount host SSH keys into the dev container when available
* switch RFS to git builds, register the zosstorage source, and document the extra Rust component
* wire zosstorage into the build: add build_zosstorage(), ship the binary in the initramfs, and extend component validation
* refresh kernel configuration to 6.12.49 while dropping Xen guest selections and enabling counted-by support
* tighten runtime configs: use cached mycelium key path, add zosstorage zinit unit, bootstrap ovsdb-server, and enable openvswitch module
* adjust the network health check ping invocation and fix the RFS pack-tree --debug flag order
* update NOTES changelog, README component list, and introduce a runit helper for qemu/cloud-hypervisor testing
* add ovsdb init script wiring under config/zinit/init and ensure zosstorage is available before mycelium
