Add Python install orchestrator (moved from omarchy-installer)

The orchestrator drives an offline install on the live ISO using
archinstall as a library subsystem. Lands under configs/airootfs/ so
mkarchiso bakes it into the live squashfs directly:

  /usr/share/omarchy-iso/orchestrator/   (the Python package)
  /usr/local/bin/omarchy-iso-install     (thin shell wrapper that
                                          execs python -m orchestrator.main)

Two corrections vs the previous omarchy-installer location:

1. omarchy-installer dropped from EARLY_PACKAGES \u2014 it's live-ISO-only
   install tooling, must never land on the target. /etc/skel is still
   populated pre-useradd via omarchy-settings.

2. run_chroot_finalizer now copies /usr/share/omarchy from the live
   ISO into /mnt/tmp/omarchy-install/ before arch-chroot. finalize.sh
   + install/ scripts run from /tmp inside the chroot; /tmp is wiped
   on first reboot, so the target boots with zero install detritus.

configs/airootfs/usr/local/bin/omarchy-iso-install

@@ -0,0 +1,14 @@
+#!/bin/bash
+#
+# Live-ISO entry point for the Omarchy install orchestrator. Invoked from
+# /root/.automated_script.sh after the configurator wizard has produced
+# user_configuration.json / user_credentials.json / user_full_name.txt /
+# user_email_address.txt / user_encrypt_installation.txt.
+#
+# Just sets cwd so 'python -m orchestrator.main' can find the package,
+# then hands off all args.
+
+set -eEo pipefail
+
+cd /usr/share/omarchy-iso
+exec python -m orchestrator.main "$@"