refactor(EnvelopeController): migrate envelope update to MediatR with annotations

- Renamed `Update` action to `CreateOrUpdate`.
- Replaced manual signing logic with `_mediator.SignDocAsync`.
- Added `ExpandoObject` parameter to handle document annotations.
- Improved authorization checks and logging for missing claims.
- Kept legacy `Reject` endpoint intact with obsolete services.

EnvelopeGenerator.Web/wwwroot/js/app.js

@@ -277,7 +277,6 @@ class App {
                 try {
                     const json = await iJSON
                     const postEnvelopeResult = await this.Network.postEnvelope(
-                        this.envelopeKey,
                         this.currentDocument.id,
                         json
                     )