feat: ARM ISO boot integration test, OVMF boot fixes

ARM integration test:
- arm-iso-provision.test.ts: aarch64 VM boots from bastion-generated ISO
- Uses QEMU aarch64 emulation (slow but validates the R1 scenario)
- Generous timeouts for emulated boot (15min discovery, 60min install)
- test-provision.sh updated: `sudo ./scripts/test-provision.sh arm`

VM boot fixes:
- setBootDisk() preserves UEFI loader/nvram when switching to disk boot
- /boot/efi mount gets nofail in fstab (prevents emergency mode in VMs)
- chronyd enable uses || true (fails in kickstart chroot)
- createIsoVm supports arch parameter for ARM VMs

Note: SSH-after-reboot in OVMF VMs still fails — OVMF doesn't respect
efibootmgr changes and loops PXE/HTTP Boot. Real hardware works fine.
The install flow itself (discovery → kickstart → complete) is validated.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

bastion/src/bastion/src/templates/install.ks.ts

@@ -409,6 +409,9 @@ hostnamectl set-hostname ${fqdn}
 # -- tmpfs for /tmp --
 echo "tmpfs /tmp tmpfs defaults,noatime,nosuid,nodev,size=4G 0 0" >> /etc/fstab
 
+# Make /boot/efi mount non-fatal (prevents emergency mode if EFI partition isn't found)
+sed -i '/\\/boot\\/efi/ s/defaults/defaults,nofail/' /etc/fstab
+
 ${isVanilla ? `# -- vanilla role: skip k3s kernel/sysctl/firewall setup --
 bastion_progress "post-install" "vanilla role -- skipping k3s setup"
 # -- Enable chronyd for time sync --