Analyze an invoice or receipt with the Azure AI Document Intelligence prebuilt-invoice model over REST, handling the 202 Operation-Location polling pattern and per-field confidence

Documented steps

1. Provision a Document Intelligence resource and note the endpoint https://{resource}.cognitiveservices.azure.com plus either a key or an Entra ID identity.
2. Authenticate with header 'Ocp-Apim-Subscription-Key: {key}', or with 'Authorization: Bearer {token}' from DefaultAzureCredential. Python SDK package is azure-ai-documentintelligence, which targets API version 2024-11-30.
3. POST {endpoint}/documentintelligence/documentModels/prebuilt-invoice:analyze?_overload=analyzeDocument&api-version=2024-11-30 with Content-Type application/json. Swap in prebuilt-receipt for receipts.
4. Body is either {"urlSource":"https://...pdf"} for a hosted file or {"base64Source":"<base64 bytes>"} for inline content.
5. The service returns 202 Accepted with an empty body. Read the Operation-Location response header, which looks like {endpoint}/documentintelligence/documentModels/prebuilt-invoice/analyzeResults/{resultId}?api-version=2024-11-30.
6. Poll GET on that exact Operation-Location URL with the same auth header and api-version. Do not poll more often than roughly once every 2 seconds.
7. Stop when the top-level 'status' field is 'succeeded' or 'failed'. On success the body contains analyzeResult.{apiVersion, modelId, content, pages, tables, documents}.
8. Iterate analyzeResult.documents[]: each has docType (e.g. 'invoice'), a document-level confidence, and a fields map keyed by names such as VendorName, CustomerName, InvoiceId, InvoiceTotal and Items, each carrying its own type, value, content and confidence (0-1 scale).
9. Response schema reference: https://learn.microsoft.com/en-us/rest/api/aiservices/document-models/get-analyze-result?view=rest-aiservices-v4.0+(2024-11-30)
10. SDK shortcut: DocumentIntelligenceClient.begin_analyze_document('prebuilt-invoice', AnalyzeDocumentRequest(url_source=...)) with WaitUntil.Completed wraps the POST, header read and polling loop.