Integrate zosstorage build path and runtime orchestration

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

config/zinit/mycelium.yaml

@@ -1,7 +1,8 @@
-exec: /usr/bin/mycelium --key-file /tmp/mycelium_priv_key.bin
+exec: /usr/bin/mycelium --key-file /var/cache/etc/mycelium_priv_key.bin
   --tun-name my0 --silent --peers tcp://188.40.132.242:9651 tcp://136.243.47.186:9651
   tcp://185.69.166.7:9651 tcp://185.69.166.8:9651 tcp://65.21.231.58:9651 tcp://65.109.18.113:9651
   tcp://209.159.146.190:9651 tcp://5.78.122.16:9651 tcp://5.223.43.251:9651 tcp://142.93.217.194:9651
 after:
   - network
-  - udev-rfs
+  - udev-rfs
+  - zosstorage