Open a period in the ledger, or return the one already open

Records that somebody intends to work on this month. IT SENDS NOTHING TO SUNAT, which is why it needs only sire:read — requiring sire:manage would make looking impossible without also holding the capability to close a period. Idempotent by the schema: one operation per (company, book, period), so a repeat returns the one that exists rather than starting a second. Reopening never resets a period that is already awaiting a ticket. A COMPANY IN BETA IS REFUSED with 409 SIRE_REQUIRES_PRODUCTION. SIRE only knows real RUCs and has no test environment: it is not that a beta company would fail, it is that there is nowhere for it to try. The refusal comes from the database, not from this route.

curl -X POST "https://example.com/api/v2/sire/periods" \  -H "Authorization: Bearer apf_v2_tu_credencial" \  -H "Content-Type: application/json" \  -d '{    "book": "rvie",    "period": "202412"  }'

{  "schemaVersion": "2.0",  "requestId": "d385ab22-0f51-4b97-9ecd-b8ff3fd4fcb6",  "book": "rvie",  "period": "string",  "status": "PENDING",  "ticket": "string",  "sunat": {    "code": "string",    "message": "string"  },  "updatedAt": "2019-08-24T14:15:22Z",  "history": [    {      "status": "string",      "detail": "string",      "at": "2019-08-24T14:15:22Z"    }  ]}