feat: add BVK exchange library

logger.go

@@ -0,0 +1,19 @@
+package mila
+
+import "log/slog"
+
+type Option func(*Handler)
+
+func WithLogger(logger *slog.Logger) Option {
+	return func(h *Handler) {
+		if logger != nil {
+			h.logger = logger
+		}
+	}
+}
+
+func WithOnSet(fn func(ContentState)) Option {
+	return func(h *Handler) {
+		h.onSet = fn
+	}
+}