feat(user-manager-client): stateful sub-workspace lifecycle mock handlers (LLMO-5616)

[byteclimber]

What

Makes the sub-workspace provisioning lifecycle stateful and deterministic in the User Manager Counterfact mock. The three endpoints spacecat-api-service's market-mirror provisioning calls were still auto-generated random stubs, so the provisioning poll never reliably read the success state and sub-workspace creation hung/failed against the mock:

• POST /v2/workspaces/{id}/child — random id
• GET /v1/workspaces/{id}/status — random status
• POST /v2/workspaces/{id}/resources/transfer — random 200

How

Hand-authored stateful handlers delegating to $.context (mirroring the existing v1/workspaces/{id}/child pattern), surviving Counterfact regeneration (append-don't-clobber on existing route files):

• _.context.ts — getStatus (terminal created; seedable not ready → created sequence), setStatusSequence, transferResources; statusSequences re-seeded on reset().
• v2 child / v1 status / v2 transfer — random stubs → stateful.
• __set-status-sequence — non-spec control route (like __reset) to drive the poll path deterministically.
• mock.test.js — E2E for the full create → status → transfer chain, the poll sequence, and missing-workspace paths.

Notes

• Success status is created, not ready. That's the value the api-service transport polls for, per the merged overlay's CR2 (status.status === 'created'); ready isn't in the WorkspaceCheckResponse enum.
• Scope: strictly the three endpoints in the issue. Deliberately did not touch family or add a transfer balance guard — both would bake unvalidated behavior into the mock (the consumer path isn't live-validated yet).
• Stacked on PR feat(user-manager-client): stateful Counterfact mock with seed/reset + E2E (LLMO-5616) #1685 (feat/llmo-5616-user-manager-mock), since the mock infrastructure isn't on main yet. Will retarget to main once feat(user-manager-client): stateful Counterfact mock with seed/reset + E2E (LLMO-5616) #1685 merges.
• Independent of the overlay work (feat(user-manager-client): generation-time OpenAPI overlay for spec corrections #1699), which is already merged to main.

Validation

• npm test -w packages/spacecat-shared-user-manager-client — 30 passing (8 new), 100% coverage.
• npm run lint -w packages/spacecat-shared-user-manager-client — clean.

Closes #1700

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