mempool+server: wire StandardPackageAnalyzer into TxMempoolV2

This commit integrates the StandardPackageAnalyzer into the v2 mempool
initialization flow, enabling TRUC validation for all transactions
processed through TxMempoolV2. The analyzer is constructed during server
initialization and passed to the transaction graph through GraphConfig.

When the --usetxmempoolv2 flag is enabled, the server now creates a
StandardPackageAnalyzer instance and configures it in the graph. This
enables automatic enforcement of BIP 431 rules during transaction
acceptance without requiring explicit validation calls in the mempool
logic, as the graph handles package identification and validation
internally.

Convenience wrapper functions NewStandardPackageAnalyzer and
DefaultGraphConfig in the mempool package simplify server initialization
while keeping the txgraph package focused on graph operations. This
layering prevents circular dependencies and maintains clean separation
between graph logic and higher-level mempool policy.

Author: Roasbeef

mempool/mempool_v2.go

@@ -902,5 +902,17 @@ func (mp *TxMempoolV2) CheckMempoolAcceptance(tx *btcutil.Tx) (*MempoolAcceptRes
 	return mp.checkMempoolAcceptance(tx, true, false, true)
 }
 
+// NewStandardPackageAnalyzer creates a new standard package analyzer for TRUC
+// (BIP 431) validation. This is a convenience wrapper for the txgraph package.
+func NewStandardPackageAnalyzer() *txgraph.StandardPackageAnalyzer {
+	return txgraph.NewStandardPackageAnalyzer()
+}
+
+// DefaultGraphConfig returns the default txgraph configuration. This is a
+// convenience wrapper for the txgraph package.
+func DefaultGraphConfig() *txgraph.Config {
+	return txgraph.DefaultConfig()
+}
+
 // Ensure TxMempoolV2 implements the TxMempool interface.
 var _ TxMempool = (*TxMempoolV2)(nil)

server.go

@@ -3214,6 +3214,13 @@ func (s *server) initTxMempoolV2(cfg *config, chainParams *chaincfg.Params) (mem
 	}
 	orphanManager := mempool.NewOrphanManager(orphanCfg)
 
+	// Create PackageAnalyzer for TRUC (BIP 431) validation.
+	packageAnalyzer := mempool.NewStandardPackageAnalyzer()
+
+	// Create GraphConfig with package analyzer.
+	graphCfg := mempool.DefaultGraphConfig()
+	graphCfg.PackageAnalyzer = packageAnalyzer
+
 	// Create MempoolConfig with all dependencies.
 	mempoolCfg := &mempool.MempoolConfig{
 		FetchUtxoView:  s.chain.FetchUtxoView,
@@ -3224,7 +3231,7 @@ func (s *server) initTxMempoolV2(cfg *config, chainParams *chaincfg.Params) (mem
 		OrphanManager:  orphanManager,
 		AddrIndex:      s.addrIndex,
 		FeeEstimator:   s.feeEstimator,
-		GraphConfig:    nil, // Use defaults.
+		GraphConfig:    graphCfg,
 	}
 
 	return mempool.NewTxMempoolV2(mempoolCfg)