feat(foreign-port): add WiFi-only laptop as clan machine ✨

Mirrors the distant-shore pattern: clan-managed (no standalone
flake-module), wired into zerotier/data-mesher/dm-pull-deploy with the
generated vars. WiFi via NetworkManager (PSK from /etc/secrets/nm.env);
locally-signed boot chain (shim chain-loads sbsign-signed systemd-boot
+ kernel, refreshed every nixos-rebuild). targetHost is the LAN IP for
the first push, switch to ZT IPv6 once on the mesh. buildHost =
sunken-ship to avoid self-SSH on the closure copy.

sops/machines/foreign-port/key.json

@@ -0,0 +1,6 @@
+[
+  {
+    "publickey": "age1lwl2z6ymqjshknr79277qnr7hvffcc8n7qdqt98sz3t709a5yutq8d7gka",
+    "type": "age"
+  }
+]