[Feature]: Display subscription info in org settings

[SuaYoo]

Mockups

Backend changes

• Update helm chart to include new settings
• New fields in GET /api/settings:
  • Required: Is billing/subscriptions enabled?
  • Sales email address
• New GET /api/orgs/{oid}/billing endpoint with fields:
  • Required: Subscription status, one of 'active', 'canceled', 'incomplete', 'incomplete_expired', 'past_due', 'paused', 'trialing', 'unpaid'
  • Link to manage plan
  • Next payment date (nice to have)
  • Date subscription ends (free trial or expiring subscription) (nice to have)

Frontend changes

• Show billing tab in org settings if billing is enabled in app settings
• Show billing tab content like link to Stripe portal (if subscription_id in org) or “Contact sales”

[ikreymer]

Current impl in progress: /api/orgs/{oid}/billing returns {"subUrl": <Subscription URL>, "subStatus": <Subscription Status>}

[SuaYoo]

@ikreymer @emma-sg could the backend API also return a subscription type of self-service or managed? That way we don't need to deal with details of all the subscription tiers right now, but we can handle showing different UI for the two. Per Discord convo, billing will return a null subscription object, from which the tier will be inferred for now.