fix: shared renamed to pkg, formatting changes

pkg/plugin/definition/publisher.go

@@ -0,0 +1,16 @@
+package definition
+
+import "context"
+
+// Publisher defines the general publisher interface for messaging plugins.
+type Publisher interface {
+	// Publish sends a message (as a byte slice) using the underlying messaging system.
+	Publish(ctx context.Context, msg []byte) error
+
+	Close() error // Important for releasing resources.
+}
+
+type PublisherProvider interface {
+	// New initializes a new publisher instance with the given configuration.
+	New(ctx context.Context, config map[string]string) (Publisher, error)
+}