Merge all the server components

pkg/lazy/lazy.go

@@ -0,0 +1,27 @@
+package lazy
+
+import "sync"
+
+// Lazy is an object that a lazily-initialized value of type T.
+//
+// A Lazy must not be copied after first use.
+type Lazy[T any] struct {
+	once  sync.Once
+	value T
+}
+
+// Get returns the value associated with this Lazy.
+//
+// If no other call to Get has started or completed an initialization, initializes the value using the init function.
+// Otherwise, it returns the initialized value.
+//
+// If init panics, the initization is considered to be completed.
+// Future calls to Get() do not invoke init, and the zero value of T is returned.
+//
+// Get may safely be called concurrently.
+func (lazy *Lazy[T]) Get(init func() T) T {
+	lazy.once.Do(func() {
+		lazy.value = init()
+	})
+	return lazy.value
+}