chore: replace real IPs in docs and configs with placeholders

Operator-facing IPs in user-visible configs/docs (examples, tutorials,
packaging, sidecar templates) are now the resolvable hostnames of the
public test fleet (test-us01.fips.network, etc.) so they keep working
without baking specific addresses into examples.

Doc-comment and test fixtures in src/config/transport.rs use RFC 5737
TEST-NET-2 (198.51.100.1) so they cannot accidentally point at a real
host.

Also resyncs the openwrt-ipk fips.yaml with the common reference
(merge from master) and applies the same DNS-name swap there.

examples/wireguard-sidecar-macos/fips.yaml

@@ -32,5 +32,5 @@ peers:
     alias: "fips-test-node"
     addresses:
       - transport: udp
-        addr: "217.77.8.91:2121"
+        addr: "test-us01.fips.network:2121"
     connect_policy: auto_connect