Post Inventory Update

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sequenceDiagram
    autonumber
    participant Partner as Partner Integration
    participant API as REST API
    participant GCS as Google Cloud Storage
    rect rgb(250,238,218)
    Note over Partner,API: 1. Request Signed URL
    Partner->>+API: POST /inventory { "callbackUrl": "..." }
    API->>+GCS: Request Signed URL
    GCS-->>-API: Return Signed URL + Required Headers
    API-->>-Partner: 200 OK { "signedUrl": "...", "headers": {...} }
    end
    rect rgb(250,238,218)
    Note over Partner,GCS: 2. Submit JSONL (Within 15m)
    Partner->>+GCS: PUT Inventory JSONL to Signed URL (with Required Headers)
    GCS-->>-Partner: 200 OK (Upload Accepted)
    end
    rect rgb(250,238,218)
    Note over GCS: 3. Asynchronous Processing
    GCS->>GCS: Process Inventory JSONL
    end
    rect rgb(250,238,218)
    Note over GCS,Partner: 4. Completion Callback
    GCS->>+Partner: POST callbackUrl { status: "processed" }
    Partner-->>-GCS: 200 OK
    end