Install matching kernel headers for every DKMS setup

(cherry picked from commit 662051ecde)

migrations/1789444024.sh

@@ -0,0 +1,8 @@
+echo "Install missing headers for the Omarchy or T2 kernel"
+
+# Fresh ISO installs mark earlier migrations complete, so the kernel migration
+# cannot repair headers omitted by those installers. Package installation is
+# idempotent when another user has already applied this repair.
+if omarchy-pkg-present linux-omarchy || omarchy-pkg-present linux-t2; then
+  omarchy-pkg-add-kernel-headers
+fi