v0.7.5 — port 9484 default + auto-increment
Default listen port is now the official IICP port 9484. iicp-node auto-increments to the next free port when 9484 is in use (N nodes → N pinholes, multiple models share one port; skipped with --public-endpoint). Fixes a borrow-after-move in the nat-feature relay path and gates relay-election helpers behind the nat feature so default-feature clippy is clean.