fix: unified raw room names + merged presence on join

1. CLI client now sends raw room names (no hash), matching Android
   JNI and Desktop Tauri. All three clients are now consistent.

2. When a client joins a global room, the relay merges federated
   remote participants into the initial RoomUpdate. Previously,
   clients that joined after the GlobalRoomActive signal only saw
   local participants. Now they see everyone immediately.

3. Added get_remote_participants() to FederationManager for querying
   cached remote participants from all peer links.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

crates/wzp-client/src/cli.rs

@@ -250,12 +250,11 @@ async fn main() -> anyhow::Result<()> {
         "WarzonePhone client"
     );
 
-    // Hash room name for SNI privacy (or "default" if none specified)
+    // Use raw room name as SNI (consistent with Android + Desktop clients for federation)
     let sni = match &cli.room {
         Some(name) => {
-            let hashed = wzp_crypto::hash_room_name(name);
-            info!(room = %name, hashed = %hashed, "room name hashed for SNI");
-            hashed
+            info!(room = %name, "using room name as SNI");
+            name.clone()
         }
         None => "default".to_string(),
     };