nextcloud/install: session-bus override, KWallet existence check, pass REPO vars

- sync_client_software.sh: add system-wide flatpak session-bus override for
  Nextcloud so KWallet D-Bus access works for all users; fix broken compound
  test ([ a || b ] → [ a ] || [ b ])
- user_run.sh: check KWallet entries with hasEntry before writing — skip write
  and print info message when both passwords are already present; remove stale
  commented-out code
- install.sh: forward REPO_URL and REPO_BRANCH into configure.sh environment
  for both the su- and direct-bash invocation paths
- configure.sh: simplify do_configure (user cleanup)

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

system_setup/configure.sh

@@ -40,12 +40,7 @@ override_conf_var() {
 
 do_configure() {
     mkdir -p "$(dirname "$CONF_FILE")"
-    cp "$CONF_DIST" "$CONF_FILE"
-
-    # Source the dist defaults (unset computed vars first so they are re-evaluated).
-    unset TLDOMAIN DOMAIN SERVERFQDN_IPA SERVERFQDN_NC CLIENTADMINGROUP \
-          DECRYPTEDDATADIR ENCRYPTEDDATADIR IPAVAULTUSE IPAVAULTNAME HOSTNM FQDN
-    # shellcheck disable=SC1090
+    cp "$CONF_DIST" "$CONF_FILE" # Either setup_system.conf or setup_system.conf.dist to config.d/configure.conf
 
     echo ""
     echo "=== System Configuration ==="