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

inc/context.h

@@ -38,6 +38,9 @@ typedef struct {
     size_t interceptCtxCount;
     flatcc_builder_t stream_builder;
     uint64_t simRateLimit;
+    // Cached DeviceIdMappingNotif broadcast message (sent to newly authed clients)
+    uint8_t* deviceIdMappingMsg;
+    size_t   deviceIdMappingMsgLen;
 } EmulContext;