ActivityPub posts should render dates properly

[mark.reeves]

Ideally all Discourse tags would be handled gracefully (rendered or omitted), but we should make sure that dates are output directly:

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Onebox renders the date nicely:

Webinar: Growing and Retaining Your Community

It’s webinar time again! Join us 2025-05-20T17:00:00Z (UTC) for a look into why people join and stay in communities! Registration Link [The image is a promotional flyer for a webinar titled "Why People Join and Stay in Communities," scheduled for May 20, 2025, at 1 PM ET, hosted by a Customer Success Team, which covers topics such as motivations for joining, barriers, building trust, and onboard strategies, with a call to... (Captioned by AI)] We’ll explore the psychology behind why people jo…