Implement notifications service with shared messaging and email drivers (#36)

backend/notifications/interface/go.mod

@@ -0,0 +1,15 @@
+module git.sendico.io/tech/sxchnge/notifications/interface
+
+go 1.27.0
+
+require (
+	google.golang.org/grpc v1.83.2
+	google.golang.org/protobuf v1.36.12
+)
+
+require (
+	golang.org/x/net v0.58.0 // indirect
+	golang.org/x/sys v0.47.0 // indirect
+	golang.org/x/text v0.41.0 // indirect
+	google.golang.org/genproto/googleapis/rpc v0.0.0-20260526163538-3dc84a4a5aaa // indirect
+)