Backfill Mesa Vulkan drivers for systems installed before vulkan.sh

Systems installed before vulkan.sh (2026-02-20) never received their Mesa
Vulkan ICD. Add a migration replaying vulkan.sh's GPU vendor detection and
idempotent omarchy-pkg-add calls to backfill Intel/AMD/Asahi drivers.

Closes #6199. Reported in #6089.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

migrations/1783625095.sh

@@ -0,0 +1,19 @@
+echo "Backfill Mesa Vulkan drivers for systems installed before vulkan.sh was added"
+
+declare -A VULKAN_DRIVERS=(
+  [Intel]=vulkan-intel
+  [AMD]=vulkan-radeon
+  [Apple]=vulkan-asahi
+)
+
+PACKAGES=()
+
+for vendor in "${!VULKAN_DRIVERS[@]}"; do
+  if lspci | grep -iE "(VGA|Display).*$vendor" > /dev/null; then
+    PACKAGES+=("${VULKAN_DRIVERS[$vendor]}")
+  fi
+done
+
+if (( ${#PACKAGES[@]} > 0 )); then
+  omarchy-pkg-add "${PACKAGES[@]}"
+fi