rackula-api.service ships with ProtectHome=true and
ExecStart=/usr/local/bin/bun. With BUN_INSTALL=/root/.bun the symlink
resolves into /root, which is masked in the unit's mount namespace, so
the service fails with status=203/EXEC and crash-loops. Use /opt/bun
instead, matching yubal and gitea-mirror.
Also drop the unused BUN_VERSION/BUN_VARIANT block (bun.sh/install
takes the version as a positional arg and detects avx2/baseline
itself, so the env vars were dead code) and restore the msg_ok
"Installed Bun" / msg_info "Setting up Rackula" pair.
Claude-Session: https://claude.ai/code/session_011sGajwSQGg1vd6m2AC6Byq
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>