ix init script duplication and CPIO creation issues

- Remove duplicate /sbin/init copying from initramfs_setup_zinit()
- Only /init should be config/init (initramfs setup script)
- No /sbin/init needed - config/init calls 'switch_root /mnt/root /sbin/zinit init'
- Remove unsupported cpio --owner option that broke CPIO creation
- Fix validation to not expect /sbin/init file
- Correct boot flow: /init → switch_root → /sbin/zinit init
- Remove strip and UPX compression from zinit binary copying
- UPX compression was corrupting the zinit binary causing segfaults after switch_root
- Keep zinit unmodified as it's

config/firmware.conf

@@ -7,7 +7,6 @@ linux-firmware-bnx2:Broadcom NetXtreme firmware
 linux-firmware-e100:Intel PRO/100 firmware
 linux-firmware-intel:Intel network and WiFi firmware (includes e1000e, igb, ixgbe, i40e, ice)
 linux-firmware-realtek:Realtek network firmware (r8169, etc.)
-linux-firmware-mellanox:Mellanox network firmware
 linux-firmware-qlogic:QLogic network firmware
 
 # Storage firmware (if needed)