Relocate dist files, fix path references, and misc script improvements

- Move setup_system.conf.dist to system_setup/config.dist/ and
  skel.tar.zst.dist + pack_skel.sh to system_setup/skel/; config/ now
  holds only gitignored local files
- Fix configure.sh CONF_DIST path (was pointing at non-existent
  config/setup_system.conf.dist)
- Fix skel/pack_skel.sh: remove vestigial source line whose path was
  wrong in both old and new location
- Update error messages in setup_system.inc.sh and
  sync_client_software.sh to reference new dist file location
- Move machine_uuid reading/writing into setup_system.inc.sh so all
  scripts have MACHINEID available; setup_system.conf.dist now uses
  MACHINEID conditionally with a hostname fallback
- sync_client_software.sh: fix && / typo (should be && \) that broke
  the flatpak remote-add → install chain; add network error handling
  after flatpak install; cleanup upgrade logic and chown placement
- Update CLAUDE.md and install.md to reflect new dist file locations

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

system_setup/sync_client_software.sh

@@ -20,15 +20,20 @@ fi
 
 #Install or update Nextcloud com.nextcloud.desktopclient.nextcloud
 echo "Update or install Nextcloud client"
-/usr/bin/flatpak remote-add --if-not-exists flathub https://dl.flathub.org/repo/flathub.flatpakrepo
+/usr/bin/flatpak remote-add --if-not-exists flathub https://dl.flathub.org/repo/flathub.flatpakrepo && \
 /usr/bin/flatpak install -y --or-update --noninteractive flathub com.nextcloud.desktopclient.nextcloud && echo "Done Update/Install of Nextcloud."
+if [[ $? -ne 0 ]]; then
+    echo ""
+    echo "There seems to be a problem with your network connection. Please first check, if your network can be established before reuming."
+    echo "You can press CRTL+C to abort now. Than your data wont be accessible and you need to run \"$0\" again."
+    echo "You can also continue without network. You may need your personal encryptionkey for accessing your data."
+    read -n 1 -s -r -p "Please check Network and press any Key to continue"
+fi
 echo ""
 
-#Sync remote Files
+#Do an upgrade of the Base package if its configured and if there are changes
 chown root:${CLIENTADMINGROUP} -R ${SYSCONFIGPATH}
 chmod ug+rwX,o=rX -R ${SYSCONFIGPATH}
-
-#Do an upgrade of the Base package if its configured and if there are changes
 if [[ ! -z "${UPGRADEURL}" ]]; then
     echo "Checking for Upgrades on ${UPGRADEURL} and Branch ${UPGRADEBRANCH}"
     REMOTEURL=$( git config --get remote.origin.url )
@@ -43,14 +48,17 @@ if [[ ! -z "${UPGRADEURL}" ]]; then
         else
             # Doing upgrade, discarding all local changes frist (is more save than forced pull)
             echo "Checks have passed, we are now upgrading via git."
-            git fetch origin
-            git reset --hard origin/${UPGRADEBRANCH}
-            #Remove all history
-            git rebase HEAD^
+            #Fetch latest Updates and remove all history
+            git fetch origin && git reset --hard origin/${UPGRADEBRANCH} && git rebase HEAD^
+            if [[ $? -ne 0 ]]; then
+                echo "Error: Failure while updating, will continue as is."
+            fi
         fi
     fi
-    echo ""
+else
+    echo "UPGRADEURL is not specified in conf - No Upgrade option available."
 fi
+echo ""
 
 # At first, sync central configs if they are configured to be synced
 if [[ ! -z "${DISTCONFIGPATH_SRC}" ]]; then
@@ -85,12 +93,13 @@ if [[ ! -z "${DISTCONFIGPATH_SRC}" ]]; then
             echo "System is in configure-mode and configuration repository was found and synced, but still not configuration was found"
             echo "checking file $(dirname "$0")/../config/setup_system.conf"
             echo ""
-            echo "Please make a inital copy of config/setup_system.conf.dist to config/setup_system.conf and check all settings there."
+            echo "Please make a copy of system_setup/config.dist/setup_system.conf.dist to config/setup_system.conf and check all settings there."
             echo "Then rerun the logon script to sync the file to your repository."
             echo "Press any key to continue" && read -n 1 -s -r && exit 1
         fi
     fi
 fi
+
 #Check if Repository is defined
 if [ "${CLIENT_SOFTWARE_DST}." == "." ]; then
     echo "No central softwarerepository defined (CLIENT_SOFTWARE_DST). Skipping sync."