fix(retry): retry transient edge answers centrally, fix stale task test (#57)

- Route HTTP helpers (getJSON/formRequest/deleteReq/postJSON/putJSON/
  multipart upload), Query and AuthenticateContext/ensureToken through the
  deterministic 429/502/503/504 retry (retryRaw), so the integration suite
  no longer fails on the shared openresty rate limit under parallel runs.
- Fix stale cmd/office/fetch integration test: loader.TaskFields was
  replaced by loader.DetailForm (broke go vet -tags=integration).
- Add unit tests for Transient/DoRetry.

cmd/office/fetch/task_integration_test.go

@@ -4,7 +4,6 @@ package fetch_test
 
 import (
 	"context"
-	"os"
 	"testing"
 
 	"github.com/eslider/go-onlyoffice/cmd/office/model"
@@ -46,9 +45,6 @@ func TestIntegrationUpdateTaskTitleDescription(t *testing.T) {
 }
 
 func TestIntegrationTaskFieldsFromLiveAPI(t *testing.T) {
-	if os.Getenv("ONLYOFFICE_URL") == "" && os.Getenv("ONLYOFFICE_HOST") == "" {
-		t.Skip("ONLYOFFICE_URL not set")
-	}
 	loader, ctx := liveLoader(t)
 	items, err := loader.List(ctx, model.ListSpec{Subject: model.SubjectTasks})
 	if err != nil {
@@ -57,12 +53,12 @@ func TestIntegrationTaskFieldsFromLiveAPI(t *testing.T) {
 	if len(items) == 0 {
 		t.Skip("no tasks")
 	}
-	title, desc, err := loader.TaskFields(ctx, items[0])
+	fields, err := loader.DetailForm(ctx, items[0])
 	if err != nil {
 		t.Fatal(err)
 	}
-	if title == "" {
+	if fields.Primary == "" {
 		t.Fatal("empty title")
 	}
-	_ = desc
+	_ = fields.Secondary
 }