M6: provenance fixes, stored features, community edits that are real edits

- A fetched ObjectRecord no longer wears the signature, key, signed headers and @context
  of the activity that caused the fetch, and its ReceivedAt is the fetch's own time. Its
  activity fields now name the trigger. Provenance answers signature null and
  fetchedBy "instance-actor". Migration _008 clears the old fetched records.
- ObjectRecords store their ObjectFeatures extensions and context namespaces (migration
  _009 fills older records in batches), so statistics can count them. Provenance reads the
  stored lists.
- ForeignAvatar.Features records what an actor document uses (ActorFeatures): featured,
  shared inbox, FEP-521a, FEP-8b32, identity proofs, Misskey fields, indexable,
  undiscoverable, locked, key size, and more.
- RemoteEdits.Apply and RemoteDeletes.Remove are shared by the Update, Delete and Announce
  handlers. A community-wrapped Update is now an edit only when newer, refreshes polls
  and media otherwise, revises the ObjectRecord and re-resolves quotes. A
  community-wrapped Delete now tombstones the object, removes its ObjectRecord, reblogs
  and timeline rows, and lowers the reply count. Any deleted quoting post lowers the
  quoted post's quote count.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01ELjqpznMFMNrJoJUj6K5p2

PrivaPub/Federation/Inbox/Handlers/AnnounceHandler.cs

@@ -1,6 +1,7 @@
 using MongoDB.Driver;
 using MongoDB.Entities;
 
+using PrivaPub.Domain.Statuses;
 using PrivaPub.Domain.Social;
 using PrivaPub.Domain.Timelines;
 using PrivaPub.Federation.Actors;
@@ -28,8 +29,14 @@ namespace PrivaPub.Federation.Inbox.Handlers
 		readonly IFanout _fanout;
 		readonly IRemoteActorService _remoteActors;
 
-		public AnnounceHandler(DbEntities dbEntities, ILocalActorService localActors, IRemotePosts remotePosts, IFanout fanout, IRemoteActorService remoteActors)
+		readonly IObjectRecords _records;
+		readonly IQuoteService _quotes;
+
+		public AnnounceHandler(DbEntities dbEntities, ILocalActorService localActors, IRemotePosts remotePosts, IFanout fanout, IRemoteActorService remoteActors,
+			IObjectRecords records, IQuoteService quotes)
 		{
+			_records = records;
+			_quotes = quotes;
 			_remoteActors = remoteActors;
 			_dbEntities = dbEntities;
 			_localActors = localActors;
@@ -172,24 +179,7 @@ namespace PrivaPub.Federation.Inbox.Handlers
 							Arrival.Drop(note == default ? "fetch-failed" : "misattributed");
 							return;
 						}
-						Arrival.Accept("edit");
-						stored.Revisions.Add(new PostRevision
-						{
-							Title = stored.Title,
-							SpoilerText = stored.SpoilerText,
-							ContentHtml = stored.ContentHtml,
-							HasContentWarning = stored.HasContentWarning,
-							EditedAt = stored.EditedAt ?? stored.CreationDate
-						});
-						stored.Title = note.Title;
-						stored.SpoilerText = note.SpoilerText;
-						stored.HasContentWarning = note.Sensitive;
-						stored.Text = note.ContentHtml;
-						stored.ContentHtml = note.ContentHtml;
-						stored.Tags = note.Tags.ToList();
-						stored.Media = note.Attachments.ToList();
-						stored.EditedAt = note.Updated ?? DateTime.UtcNow;
-						await DB.Default.SaveAsync(stored, token);
+						Arrival.Accept(await RemoteEdits.Apply(stored, note, Id(inner), _localActors, _records, _quotes, token) ? "edit" : "refresh");
 					}
 					break;
 				case "Delete" when objectUri != default:
@@ -207,8 +197,7 @@ namespace PrivaPub.Federation.Inbox.Handlers
 							return;
 						}
 					Arrival.Accept("removed");
-					await DB.Default.DeleteAsync<PostEntity>(deleted.ID);
-					await DB.Default.DeleteAsync<TimelineEntry>(e => e.PostId == deleted.ID);
+					await RemoteDeletes.Remove(deleted, objectUri, token);
 					break;
 				default:
 					Arrival.Drop("unsupported");