feat: complete remaining jetstream parity implementation plan

src/NATS.Server/Raft/RaftNode.cs

@@ -79,6 +79,16 @@ public sealed class RaftNode
         Log.AppendReplicated(entry);
     }
 
+    public Task TryAppendFromLeaderAsync(RaftLogEntry entry, CancellationToken ct)
+    {
+        _ = ct;
+        if (entry.Term < TermState.CurrentTerm)
+            throw new InvalidOperationException("stale term append rejected");
+
+        ReceiveReplicatedEntry(entry);
+        return Task.CompletedTask;
+    }
+
     public async Task<RaftSnapshot> CreateSnapshotAsync(CancellationToken ct)
     {
         var snapshot = new RaftSnapshot