2configs.retiolum: chown /etc/tinc/retiolum to tinc-retiolum
Upstream NixOS tinc module's preStart chowns hosts/ and invitations/
but not the network dir itself, so tincr can't persist the per-peer
address bootstrap cache it tries to write under /etc/tinc/retiolum/
addrcache/. The save fails with "Permission denied" (debug-only), the
cache stays empty, and retries to peers without a live meta-conn fall
back to DNS instead of the last-known address. Drop this tmpfiles rule
once nixpkgs#520533 lands.
Assisted-by: Claude Code (claude-opus-4-7)