Add native NixOS deployment and UI-managed provider credentials

internal/app/app_test.go

@@ -86,9 +86,12 @@ func TestFailedClassificationStillImportsAndRetryIsIdempotent(t *testing.T) {
 		t.Fatalf("import not visible in analytics: %+v", dash.Totals)
 	}
 }
-func mockClassifier(t *testing.T, a *App) {
+func mockClassifier(t *testing.T, a *App, inspect ...func(*http.Request)) {
 	t.Helper()
 	mock := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		for _, check := range inspect {
+			check(r)
+		}
 		var req struct {
 			Messages []struct {
 				Content string `json:"content"`