feat: federation media forwarding WORKING — global rooms router model complete

2-relay test: 5.0s audio, RMS 4748, PASS. Full pipeline verified:
- Room correctly identified as global (hash matching works)
- Federation egress channel created and connected
- GlobalRoomActive signals exchanged between peers
- 300 packets (250 source + 50 FEC) forwarded via tagged datagrams
- Client B on relay B received full 5-second tone from client A on relay A

Added debug logging: is_global check, egress channel creation, per-peer
forwarding with active_rooms diagnostic when no match found. Also logs
egress packet count (first + every 250th).

Multi-hop propagation: GlobalRoomActive signals forwarded to other peers
so A→B→C chain knows about rooms across the full mesh.

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

crates/wzp-relay/src/main.rs

@@ -721,12 +721,15 @@ async fn main() -> anyhow::Result<()> {
                     .collect();
                 // Set up federation media channel if this is a global room
                 let federation_tx = if let Some(ref fm) = federation_mgr {
-                    if fm.is_global_room(&room_name) {
+                    let is_global = fm.is_global_room(&room_name);
+                    info!(room = %room_name, is_global, "checking if room is global for federation");
+                    if is_global {
                         let (tx, rx) = tokio::sync::mpsc::channel(256);
                         let fm_clone = fm.clone();
                         tokio::spawn(async move {
                             wzp_relay::federation::run_federation_media_egress(fm_clone, rx).await;
                         });
+                        info!(room = %room_name, "federation media egress channel created");
                         Some(tx)
                     } else {
                         None