Meta OAuth — dev tester

End-to-end smoke for the Meta (Facebook / Instagram) OAuth connect flow. Confirms server-side env config, runs the full bounce (/auth/meta/connect → Facebook dialog → /auth/meta/callback), persists per-org tokens via Infisical, then proves the saved token works by listing the user's ad accounts via the Graph API. Disconnect clears the org's token locally (upstream revoke is a follow-up).