Fix Kura self-host image to ship Tuist auth hook

Published Kura runtime images now include the Tuist auth extension hook at /etc/kura/extensions/tuist.lua, matching what the source Dockerfile already documented after 0.11.0. Self-host operators following the standalone guide also get a corrected setup: KURA_NODE_URL is treated as the single-node identity it has always been, the Tuist auth variables and multi-node peer/mesh variables are documented separately for when they actually apply, and the self-host ClickHouse stack now pins clickhouse/clickhouse-server:26.5-alpine with a note on preparing writable host directories for bind mounts.