Simplify OMARCHY_INSTALL_MODE to online/offline only

Drop online-git: the new world has a single package-backed install path
that's either online (pacman pulls from omacom-pkgs.org) or offline (ISO
chroot pulls from the bundled mirror). The git-clone-and-run-installer
path is gone — boot.sh becomes a thin bootstrap that installs the
omarchy-installer package and invokes its installer.

- install/helpers/mode.sh: two modes, validation message updated. Default
  fallback is 'online' (the boot.sh path); OMARCHY_CHROOT_INSTALL=1 still
  shims to offline, OMARCHY_ONLINE_INSTALL=true still shims to online.
- install/preflight/all.sh: first-run-mode + disable-mkinitcpio gated on
  offline (offline is the from-scratch chroot path; online runs on an
  existing system).
- install/preflight/pacman.sh: DELETED. boot.sh now handles repo config
  before install.sh runs.
- install/packaging/all.sh: drop base.sh entirely. Both modes have
  base packages installed via omarchy-installer's depends before
  install.sh runs. base.sh remains on disk in case the ISO mirror build
  flow wants to invoke it directly.
- install/helpers/chroot.sh, errors.sh, post-install/finished.sh,
  config/mise-work.sh: rename mode checks to use online/offline.

install/helpers/chroot.sh

@@ -1,6 +1,6 @@
-# In iso-chroot mode systemd isn't running, so skip --now and just enable.
+# In offline (ISO chroot) mode systemd isn't running, so skip --now.
 chrootable_systemctl_enable() {
-  if install_mode_is iso-chroot; then
+  if install_mode_is offline; then
     sudo systemctl enable $1
   else
     sudo systemctl enable --now $1

install/helpers/errors.sh

@@ -104,8 +104,7 @@ catch_errors() {
   while true; do
     options=()
 
-    # Retry only makes sense for online flows (git clone or package install).
-    if install_mode_is online-git || install_mode_is online-package; then
+    if install_mode_is online; then
       options+=("Retry installation")
     fi
 

install/helpers/mode.sh

@@ -1,14 +1,18 @@
-# OMARCHY_INSTALL_MODE is one of: iso-chroot, online-package, online-git
-# Back-compat shims honor the older OMARCHY_CHROOT_INSTALL and
-# OMARCHY_ONLINE_INSTALL flags during transition.
+# OMARCHY_INSTALL_MODE is one of: online, offline
+#   online  - bootstrap installed omarchy-* packages from the omacom-pkgs.org
+#             repo on an existing Arch system, then ran install.sh.
+#   offline - ISO build: archinstall pacstrapped the bundled mirror; install.sh
+#             runs in the chroot before the user's first boot.
+# Legacy OMARCHY_CHROOT_INSTALL and OMARCHY_ONLINE_INSTALL still work as
+# shims during transition.
 
 detect_install_mode() {
   if [[ -n ${OMARCHY_INSTALL_MODE:-} ]]; then
     case $OMARCHY_INSTALL_MODE in
-      iso-chroot|online-package|online-git) ;;
+      online|offline) ;;
       *)
         echo "Error: invalid OMARCHY_INSTALL_MODE=$OMARCHY_INSTALL_MODE" >&2
-        echo "       must be one of: iso-chroot, online-package, online-git" >&2
+        echo "       must be one of: online, offline" >&2
         exit 1
         ;;
     esac
@@ -17,13 +21,11 @@ detect_install_mode() {
   fi
 
   if [[ -n ${OMARCHY_CHROOT_INSTALL:-} ]]; then
-    export OMARCHY_INSTALL_MODE=iso-chroot
+    export OMARCHY_INSTALL_MODE=offline
   elif [[ -n ${OMARCHY_ONLINE_INSTALL:-} ]]; then
-    export OMARCHY_INSTALL_MODE=online-git
-  elif [[ ${OMARCHY_PATH:-} == /usr/share/omarchy ]]; then
-    export OMARCHY_INSTALL_MODE=online-package
+    export OMARCHY_INSTALL_MODE=online
   else
-    export OMARCHY_INSTALL_MODE=online-git
+    export OMARCHY_INSTALL_MODE=online
   fi
 }
 
@@ -32,22 +34,17 @@ install_mode_is() {
 }
 
 # Synchronize the legacy vars to the canonical mode so callers that still
-# check OMARCHY_CHROOT_INSTALL / OMARCHY_ONLINE_INSTALL agree with us
-# (including unsetting contradictory ones).
+# check OMARCHY_CHROOT_INSTALL / OMARCHY_ONLINE_INSTALL agree with us.
 export_legacy_mode_flags() {
   case ${OMARCHY_INSTALL_MODE:-} in
-    iso-chroot)
+    offline)
       export OMARCHY_CHROOT_INSTALL=1
       unset OMARCHY_ONLINE_INSTALL
       ;;
-    online-git)
+    online)
       export OMARCHY_ONLINE_INSTALL=true
       unset OMARCHY_CHROOT_INSTALL
       ;;
-    online-package)
-      unset OMARCHY_CHROOT_INSTALL
-      unset OMARCHY_ONLINE_INSTALL
-      ;;
   esac
 }