fix(console): discontinue first-month Go discount

[fwang]

Summary

• update workspace Go signup pricing across all console locales
• update free-limit Go upsell pricing across all UI locales and server fallback
• stop automatically applying the first-month 50% coupon at checkout while preserving explicit promotional coupons

Testing

• bun typecheck in packages/console/app
• bun typecheck in packages/console/core
• bun typecheck in packages/ui
• bun typecheck in packages/app
• bun typecheck in packages/opencode
• bun test test/session/retry.test.ts --timeout 30000 in packages/opencode
• repository pre-push typecheck