zinit: stabilize ntp/network/getty runtime

• ntp: robust /etc/ntp.conf symlink, safe defaults, avoid nounset, keep BusyBox CLI -p usage

• network: wrap dhcpcd to create dhcpcd user/group if missing; run as root if needed

• console: set getty console to 115200 vt100

config/zinit/shm.yaml

@@ -1,2 +1,5 @@
 exec: /etc/zinit/init/shm.sh
-oneshot: true
+oneshot: true
+after:
+  - firmware
+  - modules