Restore the server() test helper that the v1.1.7 tag left out.

The tag carries api/api_authentication_test.go, which calls server(), but
not api/helpers_test.go, where upstream main defines it:
https://github.com/PlakarKorp/plakar/commit/1402c42194e55d0b8f1ba49513ac30980838d402
Only server() is taken from main. Drop this patch when the release branch
carries it.

--- /dev/null
+++ b/api/helpers_test.go
@@ -0,0 +1,32 @@
+package api
+
+import (
+	"bytes"
+	"net/http"
+	"testing"
+
+	"github.com/PlakarKorp/kloset/repository"
+	"github.com/PlakarKorp/kloset/snapshot"
+	"github.com/PlakarKorp/plakar/appcontext"
+	ptesting "github.com/PlakarKorp/plakar/testing"
+)
+
+// server builds a real repository with a richer snapshot than newAPIServer
+// (nested dirs, multiple files) and wires SetupRoutes with norefresh=true.
+// Distinct name to avoid clashing with the team's newAPIServer helper.
+func server(t *testing.T, token string) (*http.ServeMux, *repository.Repository, *snapshot.Snapshot, *appcontext.AppContext) {
+	t.Helper()
+	repo, ctx := ptesting.GenerateRepository(t, bytes.NewBuffer(nil), bytes.NewBuffer(nil), nil)
+	snap := ptesting.GenerateSnapshot(t, repo, []ptesting.MockFile{
+		ptesting.NewMockDir("subdir"),
+		ptesting.NewMockFile("subdir/dummy.txt", 0644, "hello dummy"),
+		ptesting.NewMockFile("subdir/foo.txt", 0644, "hello foo"),
+		ptesting.NewMockFile("subdir/noext", 0644, "hello noext"),
+		ptesting.NewMockDir("subdir/nested"),
+		ptesting.NewMockFile("subdir/nested/deep.txt", 0644, "deep content"),
+		ptesting.NewMockFile("top.txt", 0644, "top level"),
+	})
+	mux := http.NewServeMux()
+	SetupRoutes(mux, repo, ctx, token, true /* norefresh */)
+	return mux, repo, snap, ctx
+}