Support collecting avatars from Nostr KIND 0 events

Goal

Pull in avatars with Nostr Metadata update events.

What needs to be done

Nostr provides a url for avatars. We need to scrape this and pass through to our avatar service.

QA

Avatar changes should pull into Minds.

UX/Design

N/A

Personas

Nomads

Experiments

N/A

Acceptance Criteria

• Nostr KIND 0 avatar/profile pic changes are reflected on Minds
• Ensure we only scrape external urls. Security.
• Spec tests

Definition of Ready Checklist

• Definition Of Done (DoD)
• Acceptance criteria
• Weighted
• QA
• UX/Design
• Personas
• Experiments