fix: prevent QUIC heartbeat stalls and isolate TCP retransmission counters [CI] [SKIP TESTS]

backend/shared/MoShiro.Protocol/Catalog/Kinds/Kinds.cs

@@ -22,6 +22,7 @@ public static class Kinds
         [
             Col.TsLocal("ts"), Col.U8("side"), Col.U32("srtt_us"), Col.U32("rttvar_us"), Col.U32("cwnd"),
             Col.U32("retrans_total"), Col.U32("segs_out"), Col.U64("bytes_acked"),
+            new ColumnSpec("conn", ColumnType.U64, ColumnEnc.Plain, true),
         ],
         Union: true);