Add linux-grub-repair script to automate GRUB re-installation on failed Linux VMs

[Copilot]

GRUB corruption is a recurring boot failure scenario with no dedicated automated repair path. This adds a focused linux-grub-repair script that handles GEN1 and GEN2 cases, and updates linux-alar2 docs to surface all available ALAR2 actions.

Changes

• New src/linux/linux-grub-repair.sh — dedicated script wrapping ALAR2's grubfix/efifix actions:

  • Auto-detects GEN1 vs GEN2 by checking /sys/firmware/efi/efivars; runs grubfix (GEN1) or efifix (GEN2/EFI) accordingly
  • Accepts an optional override parameter (grubfix or efifix) with input validation
  • Fails fast with a clear error if the ALAR script download fails

• Updated src/linux/linux-alar2.sh — expanded header docs to enumerate all supported ALAR2 actions (grubfix, efifix, auditd, sudo, corrupt) with descriptions and a multi-action usage example

• Updated map.json — registers linux-grub-repair as a new run-id

Usage

# Auto-detect GEN1/GEN2 and reinstall GRUB
az vm repair run -g RGNAME -n VMNAME --run-id linux-grub-repair --run-on-repair

# Force GEN1
az vm repair run -g RGNAME -n VMNAME --run-id linux-grub-repair --parameters grubfix --run-on-repair

# Force GEN2/EFI
az vm repair run -g RGNAME -n VMNAME --run-id linux-grub-repair --parameters efifix --run-on-repair