fix(console): restrict legacy access to Black - #50700

Summary

• allow only accounts with an active OpenCode Black subscription to authenticate into or continue using the legacy Console
• redirect non-Black accounts, including existing legacy sessions, to https://console.opencode.ai
• prevent the legacy auth worker from creating accounts
• replace the legacy workspace Go page with a redirect to https://console.opencode.ai/go and remove its obsolete management UI
• point public Go subscription links to the new Console
• reject legacy Go checkout creation server-side

Production check

• 1,887 workspaces have an active Black subscription
• 1,786 have a booked but inactive Black record
• none of the inactive bookings were created in the last 30 days, so access requires an active subscription_id

Verification

• bun run check

Deployment note

Stripe Checkout Sessions created before deployment remain usable until they expire. Expire open legacy Go Checkout Sessions operationally if an immediate hard cutoff is required.