Add a fedwiki-render compose service and render.sh to resolve real
Keycloak user UUIDs and render .tpl templates into testdata on compose
up.
Convert hardcoded FedWiki testdata into templates, add seed-stack.sh
helper,
and update compose/env and .gitignore to run seeding before starting
fedwiki.
Use the unified ./cmd entrypoint in test docs and bootstrap scripts
instead of ./cmd/member-console. Add derive_slug to pick a more
informative SLUG for worktrees (prefer parent dir or branch when the
basename is "member-console"). Improve teardown to remove root-owned
test files via a short-lived docker container fallback.
