tapchannel: fix allocation handling

One allocation entry means one on-chain output. So we should not create
multiple allocations for the same balance (e.g. if there are multiple
asset pieces with different asset IDs in the local or remote balance).
Instead we just create one allocation for the sum, then let the coin
distribution algorithm decide what output goes where.

Author: guggero

tapchannel/aux_closer.go

@@ -552,18 +552,10 @@ func (a *AuxChanCloser) ShutdownBlob(
 			return none, err
 		}
 
-		// We now add the a
-		// TODO(guggero): This only works if there's only a single asset
-		// in the channel. We need to extend this to support multiple
-		// assets.
-		_, err = a.cfg.AddrBook.NewAddressWithKeys(
-			ctx, address.V1, channelAsset.AssetID.Val,
-			channelAsset.Amount.Val, newKey, newInternalKey, nil,
-			*a.cfg.DefaultCourierAddr,
-		)
+		err = a.cfg.AddrBook.InsertScriptKey(ctx, newKey, true)
 		if err != nil {
-			return none, fmt.Errorf("error adding new address: %w",
-				err)
+			return none, fmt.Errorf("error declaring script key: "+
+				"%w", err)
 		}
 
 		scriptKeys[channelAsset.AssetID.Val] = *newKey.PubKey

tapchannel/aux_sweeper.go

@@ -1876,8 +1876,9 @@ func (a *AuxSweeper) resolveContract(
 		return lfn.Err[tlv.Blob](err)
 	}
 
+	type packetList = []*tappsbt.VPacket
 	var (
-		secondLevelPkts    []*tappsbt.VPacket
+		secondLevelPkts    packetList
 		secondLevelSigDesc lfn.Option[cmsg.TapscriptSigDesc]
 	)
 
@@ -1886,25 +1887,30 @@ func (a *AuxSweeper) resolveContract(
 	if needsSecondLevel {
 		log.Infof("Creating+signing 2nd level vPkts")
 
-		// We'll make a place holder for the second level output based
-		// on the assetID+value tuple.
-		secondLevelInputs := []*cmsg.AssetOutput{cmsg.NewAssetOutput(
-			assetOutputs[0].AssetID.Val,
-			assetOutputs[0].Amount.Val, assetOutputs[0].Proof.Val,
-		)}
+		// We'll make a placeholder for the second level output based
+		// on the assetID+value tuples.
+		secondLevelInputs := fn.Map(
+			assetOutputs,
+			func(a *cmsg.AssetOutput) *cmsg.AssetOutput {
+				return cmsg.NewAssetOutput(
+					a.AssetID.Val, a.Amount.Val,
+					a.Proof.Val,
+				)
+			},
+		)
 
 		// Unlike the first level packets, we can't yet sign the second
 		// level packets yet, as we don't know what the sweeping
 		// transaction will look like. So we'll just create them.
 		secondLevelPkts, err = lfn.MapOption(
 			//nolint:lll
-			func(desc tapscriptSweepDesc) lfn.Result[[]*tappsbt.VPacket] {
+			func(desc tapscriptSweepDesc) lfn.Result[packetList] {
 				return a.createSweepVpackets(
 					secondLevelInputs, lfn.Ok(desc), req,
 				)
 			},
 		)(tapSweepDesc.secondLevel).UnwrapOr(
-			lfn.Ok[[]*tappsbt.VPacket](nil),
+			lfn.Ok[packetList](nil),
 		).Unpack()
 		if err != nil {
 			return lfn.Errf[tlv.Blob]("unable to make "+