feat: late-bind dmChannelId on FederatedCallEntry when DM created mid-call

When findOrCreateDmChannel creates or finds a local channel for a
federatedId that has an active FederatedCallEntry with null dmChannelId,
update the entry. Prevents stale null references for Path B calls.

packages/server/src/routes/federation.ts

@@ -1690,6 +1690,9 @@ function findOrCreateDmChannel(
           .run();
       }
     }
+    // Late-bind: if a FederatedCallEntry exists for this federatedId with null dmChannelId,
+    // update it now that we have a local channel
+    connectionManager.lateBindFederatedCall(federatedId, existing.id);
     return existing.id;
   }
 
@@ -1715,6 +1718,10 @@ function findOrCreateDmChannel(
       .run();
   }
 
+  // Late-bind: if a FederatedCallEntry exists for this federatedId with null dmChannelId,
+  // update it now that we have a local channel
+  connectionManager.lateBindFederatedCall(federatedId, channelId);
+
   return channelId;
 }