A set of additional outbound ActivityPub outbound delivery optimizations (#4750)

* fix: remove optimistic UI updates in external actions to prevent race condition (#4711)

When adding/deleting external actions, the UI would sometimes show
duplicated or cloned rows due to a race condition between:
1. The optimistic setActions() call updating local state
2. The save() callback updating externalActions in context
3. The useEffect syncing actions from externalActions

This fix removes the optimistic updates and lets the server response
be the single source of truth, updating the UI only after the context
is updated via the save() success callback.

Fixes #4347

* fix(ap): additional outbound ActivityPub delivery optimizations

- check circuit breaker before signing any messages or any other work
- create outbound messages in batches and not all at once
- add small delay between outbound messages to spread it out a bit

* fix(ap): increase ap queue buffer size, reduce outbound http client timeout

* fix(ap): handle malformed inbox URIs

* fix(ap): batch outbox based on work performed not index

* feat(ap): add retryable activitypub outbound delivery client

---------

Co-authored-by: John Costa <jcosta@execonline.com>

activitypub/resolvers/resolve.go

@@ -11,6 +11,7 @@ import (
 	"github.com/owncast/owncast/activitypub/apmodels"
 	"github.com/owncast/owncast/activitypub/crypto"
 	"github.com/owncast/owncast/persistence/configrepository"
+	"github.com/owncast/owncast/utils"
 	"github.com/pkg/errors"
 	log "github.com/sirupsen/logrus"
 )
@@ -45,31 +46,37 @@ func Resolve(c context.Context, data []byte, callbacks ...interface{}) error {
 	return nil
 }
 
-// ResolveIRI will resolve an IRI ahd call the correct callback for the resolved type.
+// ResolveIRI will resolve an IRI and call the correct callback for the resolved type.
+// Uses a retryable HTTP client for resilience against transient failures.
 func ResolveIRI(c context.Context, iri string, callbacks ...interface{}) error {
 	configRepository := configrepository.Get()
 	log.Debugln("Resolving", iri)
 
 	req, _ := http.NewRequest(http.MethodGet, iri, nil)
+	req.Header.Set("Accept", "application/activity+json, application/ld+json")
 
 	actor := apmodels.MakeLocalIRIForAccount(configRepository.GetDefaultFederationUsername())
 	if err := crypto.SignRequest(req, nil, actor); err != nil {
 		return err
 	}
 
-	response, err := http.DefaultClient.Do(req)
+	client := utils.GetRetryableHTTPClient()
+	response, err := client.Do(req)
 	if err != nil {
 		return err
 	}
 
 	defer response.Body.Close()
 
+	if response.StatusCode >= 400 {
+		return errors.New("request failed with status: " + response.Status)
+	}
+
 	data, err := io.ReadAll(response.Body)
 	if err != nil {
 		return err
 	}
 
-	// fmt.Println(string(data))
 	return Resolve(c, data, callbacks...)
 }