Add missing acquire_lock calls to arr_sync, bulk_permissions_repair, container_data_export

arr_sync.sh had acquire_lock documented in OPERATIONAL SAFEGUARDS header but the
call was never present in the code — two sync instances could run simultaneously.
bulk_permissions_repair.sh and container_data_export.sh had no lock at all.

All three are now consistent with every other script in Media/ and Tools/.

Media/arr_sync.sh

@@ -162,6 +162,8 @@ if [[ "$EUID" -ne 0 ]]; then
     exit 1
 fi
 
+acquire_lock
+
 for _tool in curl jq; do
     if ! command -v "$_tool" >/dev/null 2>&1; then
         error "$_tool not found — required for arr API calls"