feat(console): add support workspace deletion

[opencode-agent]

Summary

• add an authenticated support endpoint for deleting one exact workspace
• revalidate the expected requester as an active workspace administrator at execution time
• reject deletion when Zen balance, reload, Black, Go, or inconsistent billing state remains
• revoke target workspace memberships, keys, provider credentials, and model overrides while preserving account data, billing history, and unrelated workspaces
• return definite preflight rejections as 4xx and ambiguous infrastructure outcomes as 5xx

Safety

• locks the exact workspace and billing state during preflight
• supports safe retries for an already-deleted target only while the original requester identity remains provable
• prevents new API-key creation after the workspace has been deleted

Tests

• bun test test/workspace.test.ts (11 passed)
• bun typecheck in packages/console/core
• bun typecheck in packages/console/app

Requested by: @MrMushrooooom (Jack via Slack)