[UX] Add 'Coming soon' indicator to incomplete features visible in UI #320

Problem

Several UI elements are visible to users but lead to dead ends or broken flows:

1. Lightning quick-action button — no handler
2. Multiple navbar links — 404
3. Price alert push channel toggle — non-functional
4. Business team invite send button — no email sent
5. Referral stats — broken API

Fix

For each incomplete feature:

1. Show a 'Coming soon' badge or tooltip
2. Disable the interactive element
3. Or hide it behind a feature flag

Impact

Medium UX — broken features damage user trust.