update proto, add config update publish broadcast, add messages compacting

flatbuffers/compacted.fbs

@@ -0,0 +1,12 @@
+namespace hmmmm;
+
+// A single serialized ServerMessage frame packed into a byte vector.
+table CompactedFrame {
+    data: [ubyte];
+}
+
+// A batch of ServerMessage frames sent as a single WebSocket frame to reduce
+// per-frame syscall overhead when message rate exceeds the batching threshold.
+table CompactedMessage {
+    frames: [CompactedFrame];
+}

flatbuffers/proto.fbs

@@ -2,6 +2,7 @@ include "auth/auth.fbs";
 include "control/control.fbs";
 include "stream/stream.fbs";
 include "mem/mem.fbs";
+include "compacted.fbs";
 
 namespace hmmmm;
 
@@ -29,6 +30,7 @@ union ServerPayload {
     hmmmm.ctrl.CtrlServerMessage,
     hmmmm.stream.StreamServerMessage,
     hmmmm.mem.MemServerMessage,
+    CompactedMessage,
 }
 
 // Every frame sent by the server is a ServerMessage.