feat(console): add idempotent Go quota repair

[opencode-agent]

Summary

Add an authenticated support endpoint for one exact reduction of a Go subscriber's current monthly consumed quota, without changing weekly/rolling usage, billing, or the subscription.

• Freeze the requester, workspace, Go user/row, customer, subscription, monthly period, expected raw counter, and expected timestamp.
• Revalidate active membership, the product binding, and active Stripe Go subscription.
• Apply an exact compare-and-set inside a transaction and preserve the monthly timestamp.
• Store the idempotency receipt atomically with the change. Identical retries return the original receipt, even after subsequent usage or a later period; conflicting key reuse is rejected.

This repairs existing state after a confirmed counter defect. It does not replace the separate inference-accounting reset-boundary fix.

Deployment

Agent-side approval tool: https://github.com/anomalyco/experiments/pull/502.

Requires the additive 20260827122435_go_quota_repair migration, then the Console endpoint deployment. No production migration or mutation has been performed. The corresponding OpenCode Agent tool will require an exact human-approved correction and validate this endpoint's structured receipt.

Verification

• TMPDIR=/tmp/opencode GO_QUOTA_REPAIR_TEST_PORT=<isolated-local-mysql-port> bun test test/go-quota-repair.test.ts test/date.test.ts test/subscription.test.ts in Console core: 69 passed, including real local MySQL transaction, concurrency, replay, stale-state, identity, expiry, and rollback coverage.
• Four route auth/input smoke checks: 4 passed, without database or Stripe calls.
• bun typecheck in Console core and Console app: passed.
• Prettier and git diff --check: passed.
• Independent review confirmed migration/snapshot only adds the receipt table and preserves existing schema.

PlanetScale and live Stripe execution have not been tested; the production action remains approval-gated.

Requested by: @MrMushrooooom (Jack via Slack)