chore: move the go code into a subfolder

apps/api/internal/eventstore/handler/v2/mock_test.go

@@ -0,0 +1,23 @@
+package handler
+
+var _ Projection = (*projection)(nil)
+
+type projection struct {
+	name     string
+	reducers []AggregateReducer
+}
+
+// ActiveInstances implements [Projection]
+func (p *projection) ActiveInstances() []string {
+	return nil
+}
+
+// Name implements [Projection]
+func (p *projection) Name() string {
+	return p.name
+}
+
+// Reducers implements [Projection]
+func (p *projection) Reducers() []AggregateReducer {
+	return p.reducers
+}