three star anniversary

[alltheseas]

[linear]

IOS-2294

[alltheseas]

Purple API Next Steps

The iOS client-side changes are ready in PR #3592. For the triple star badge to appear for three-year members, the Purple API server needs to be updated to:

1. Track membership tenure - Calculate when a user has been a continuous subscriber for more than 3 years
2. Return new attribute - Include member_for_more_than_three_years: true in the account attributes response payload

Example response format:

{
  "pubkey": "...",
  "created_at": 1700000000,
  "expiry": 1800000000,
  "subscriber_number": 42,
  "active": true,
  "attributes": {
    "member_for_more_than_one_year": true,
    "member_for_more_than_three_years": true
  }
}

The iOS app will handle the field being absent (backward compatible) - it defaults to false when missing.