implement wasm/js specific database engine

pkg/database/nip43.go

@@ -1,3 +1,5 @@
+//go:build !(js && wasm)
+
 package database
 
 import (
@@ -11,13 +13,6 @@ import (
 	"git.mleku.dev/mleku/nostr/encoders/hex"
 )
 
-// NIP43Membership represents membership metadata for NIP-43
-type NIP43Membership struct {
-	Pubkey    []byte
-	AddedAt   time.Time
-	InviteCode string
-}
-
 // Database key prefixes for NIP-43
 const (
 	nip43MemberPrefix = "nip43:member:"