feat(billing): P1f Stripe UI — admin config panel + member dues card
Settings: StripeBillingPanel (admin) — mode, publishable key, write-only
secret/webhook secret, per-tier price ids, grace days; shows the
per-space webhook URL + which events to subscribe + Portal-activation
reminder. /me: DuesCard — status from getMyBilling, 'Pay dues'
(startDuesCheckout redirect) when not active, 'Manage billing'
(startBillingPortal) when a customer exists. Self-contained client
components; settings page composes the panel after SettingsClient.
Moheeb Zara
1f61029f32