feat(network): add selectable privacy-preserving discovery

docs/README-PLAYTEST.txt

@@ -1,13 +1,18 @@
 straywild
-v0.20.2-alpha
-Alpha 0.20.2
+v0.20.3-alpha
+Alpha 0.20.3
 
 Thank you for supporting this private testing release.
 
 straywild is an early multiplayer fishing game. This alpha includes local
 progression, player-hosted and dedicated multiplayer sessions, public room
-discovery, and direct UDP connections. Expect rough edges and please keep a
-backup of any save or identity data you care about.
+discovery, player-selected direct or privacy-relayed hosting, and optional
+direct UDP connections. Player hosts can cycle discovery through private,
+direct, and relay. Dedicated servers are always direct and cannot use the
+shared relay. The relay hides peers' addresses from one another but not from
+the relay operator. Direct connections expose public IP addresses to the
+remote peer and are clearly labeled in game. Expect rough edges and please
+keep a backup of any save or identity data you care about.
 
 INSTALLATION
 
@@ -115,8 +120,9 @@ Please include:
 
 KNOWN ALPHA LIMITATIONS
 
-- Public sessions remain direct connections; restrictive NAT or carrier-grade
-  networks may prevent some players from joining.
+- Direct public sessions may fail behind restrictive NAT or carrier-grade
+  networks. Player-hosted relay sessions add an extra network hop and may have
+  more latency. Dedicated servers are direct-only.
 - Multiplayer, dedicated-server deployment, UI, and balance are still alpha.
 - Some fish and character artwork remains temporary.
 - RV exteriors and decor use temporary prototype geometry and presentation.