Handle AP Follow of non-Actor?

[snarfed]

Got a Follow of a post from Friendica today. Interesting! I know this is technical legal in AP, if uncommon. I guess it means they'd want us to deliver them replies to that post? ...which we don't support now, but I guess we could? Would take a fair amount of work to get right, but maybe doable.

https://console.cloud.google.com/errors/detail/CJ_VtIPNk9-7lwE?project=bridgy-federated

{
    "id": "https://friendica.world/objects/84b6ef2b-1368-049d-95a2-af3387728178",
    "type": "Follow",
    "actor": "https://friendica.world/profile/rodericus",
    "object": "https://bsky.brid.gy/convert/ap/at://did:plc:4j5nbrwv2u22nfvquf7pojfb/app.bsky.feed.post/3lna23pbquk23",
    "published": "2025-04-20T07:09:09Z",
    "to": [
        "https://bsky.brid.gy/ap/did:plc:4j5nbrwv2u22nfvquf7pojfb",
        "https://www.w3.org/ns/activitystreams#Public"
    ],
    "cc": ["https://friendica.world/followers/rodericus"],
    "..."
}