feat: allow users to dismiss divine login setup banner on profile

[rabble-claw]

Closes #2333

Summary

• add dismiss support to the expired divine login banner on own profile
• persist dismissal in SharedPreferences per user (dismissed_divine_login_banner_<pubkey>)
• keep existing sign-in behavior intact, but let users hide the prompt

Testing

• flutter test test/widgets/profile/profile_header_widget_test.dart
  • added coverage: session expired banner can be dismissed and stays hidden

[github-actions]

Mobile PR Preview

Property	Value
Preview URL	https://581f5b56.openvine-app.pages.dev
Pages project	openvine-app
Preview branch	pr-2214
PR branch	feat/dismiss-divine-login-banner
Commit	57282ec

[rabble]

So it's showing the registration note thing at all.

[rabble]

I pulled this back up in the remaining queue. Main open question: should dismissal reset the next time we hit an expired-session state?

As written, the dismissed banner appears to persist with no obvious reset path, so a future expired session can stay hidden. If product wants dismissal to apply only to the current expiry event, I think we need a reset trigger before merge.

[NotThatKindOfDrLiz]

@d-spurgin Can you please take a look at this in the context of your design work? You may already be addressing it? Thanks! cc @omartinma

[d-spurgin]

@NotThatKindOfDrLiz we have designs ready for this in the updated profile pages. Once we get the new designs into the dev cycle we can make this functionality available. Sound ok?