chore: add r/grc20-merkle-airdrop

examples/gno.land/r/demo/grc20-merkle-airdrop/airdrop.gno

@@ -0,0 +1,38 @@
+package grc20mtairdrop
+
+import (
+	"std"
+	"strings"
+
+	"gno.land/p/demo/airdrop"
+	"gno.land/p/demo/grc/grc20"
+
+	"gno.land/r/demo/foo20"
+)
+
+var (
+	merkleRoot string
+
+	admin std.Address = "g1sw5xklxjjuv0yvuxy5f5s3l3mnj0nqq626a9wr" // albttx.gno
+
+	airdrop *airdrop.MerkleAirdrop
+)
+
+func init() {
+	airdrop = airdrop.NewMerkleAirdrop("", token)
+}
+
+func RegisterMerkleRoot(root string) {
+	foo := foo20.Get()
+
+	// banker := std.GetBanker(std.BankerTypeOrigSend)
+	// balance := banker.GetCoins(std.GetOrigPkgAddr())
+
+	caller := std.GetOrigCaller()
+	if caller != admin {
+		panic("unauthorized")
+	}
+	airdrop.RegisterMerkleRoot(root)
+}
+
+// func Claim()