fix(planinfo): gate useOrganization() behind isSignedIn

PlanInfoProvider wraps the entire app at main.jsx, so its
useOrganization() call ran on every public-page render — Clerk logged
"useOrganization requires an active user session" on every visit to /,
/pricing, and /docs.

Split the provider in two: an outer wrapper that returns an empty
context when the user isn't signed in, and an inner ActivePlanInfoProvider
that owns the useOrganization() call and only mounts once useAuth()
reports a session.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: Sbussiso