feat(parachain): Auto-detect V2 peers from AdvertiseCollationV2 (#4711)

- Upgrade peer to ProtocolV2 when receiving V2 advertisement
- Remove redundant V1 default in PeerConnected handler
- Complete automatic version detection for collation requests

Author: Yuri0405

dot/parachain/collator-protocol/message.go

@@ -446,6 +446,9 @@ func (cpvs *CollatorProtocolValidatorSide) processCollatorProtocolMessage(sender
 			return fmt.Errorf("handling v2 advertisement: %w", err)
 		}
 
+		logger.Debugf("Peer %s sent V2 advertisement, upgrading to ProtocolV2", sender)
+		cpvs.setPeerProtocolVersion(sender, ProtocolV2)
+
 	case 4: // CollationSeconded
 		logger.Errorf("unexpected collation seconded message from peer %s, decreasing its reputation", sender)
 		cpvs.SubSystemToOverseer <- networkbridgemessages.ReportPeer{

dot/parachain/collator-protocol/validator_side.go

@@ -869,8 +869,6 @@ func (cpvs *CollatorProtocolValidatorSide) handleNetworkBridgeEvents(msg any) er
 					Instant:   time.Now(),
 				},
 			}
-			// Default to V1, will upgrade if we detect V2 capabilities later
-			cpvs.setPeerProtocolVersion(msg.PeerID, ProtocolV1)
 		}
 	case networkbridgeevents.PeerDisconnected:
 		delete(cpvs.peerData, msg.PeerID)