Add a new /subscription route showing three VIP membership plans (Monthly,
Quarterly, Annual) with a pink→peach banner, per-plan gradient price bars,
a benefits card, a mock activate CTA, and an agreement checkbox.
- New reusable <Checkbox /> in src/app/_components/core for the legal
agreement toggle
- Hardcoded SUBSCRIPTION_PLANS constant in src/data/constants
- New SubscriptionScreen composed of 7 colocated components (back link,
user row, banner, plan card, benefits card, CTA button) with CSS
Modules matching the existing design-token system
- Route registered as protected and reached from /sidebar "Membership"
- Mock CTA: window.alert + router.push(/chat) — no payment calls
Co-Authored-By: Claude <noreply@anthropic.com>