Add minimal HTTP server skeleton

Initialize Go module and create basic HTTP server structure with cmd/pkg layout. Server responds on :8080 with health check endpoint.

cmd/alpenqueue/main.go

@@ -0,0 +1,12 @@
+package main
+
+import (
+	"net/http"
+)
+
+func main() {
+	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+		w.Write([]byte("AlpenQueue running!"))
+	})
+	http.ListenAndServe(":8080", nil)
+}

go.mod

@@ -0,0 +1,3 @@
+module alpenqueue
+
+go 1.25.4