# Description of the issue/feature this PR addresses:

Nilvera uses a customized Turkish UBL format (UBL TR 1.2).

The existing Turkish UBL decoder in Odoo does not fully support TR 1.2 (CustomizationID="TR1.2"). As a result, importing such XML documents often creates invoices with missing or incomplete data because some business fields cannot be properly extracted.

# Current behavior before PR:

- Importing a TR 1.2 invoice frequently results in partially populated or empty invoices.

- The decoder lacks support for several TR 1.2-specific structures used in Nilvera electronic invoicing.

# Desired behavior after PR is merged:

- Extend the existing Turkish UBL decoder (AccountEdiXMLUblTr) to properly support UBL TR 1.2 documents.

- Reuse and enhance existing parsing logic to handle TR 1.2 specific elements while preserving compatibility with the standard UBL import flow.

- The import process now correctly extracts key invoice information, including:

  - Override Partner resolution using VKN

  - Extended postal address parsing and completion

  - Bank account prioritization from the XML document

  - Delivery details and export exemption handling

  - Product identification using default code or CTSP number

  - Tax computation for percentages, exemptions, and withholding

  - Invoice line pricing and discount extraction

- Supported scenarios are limited to:

  - ProfileID: TEMELFATURA, IHRACAT, KAMU

  - InvoiceTypeCode: SATIS, TEVKIFAT, ISTISNA, IHRACKAYITLI

  - Customer invoices and vendor bills

- Credit notes remain unsupported.

- Additional test cases ensure correct behavior for successful imports and relevant edge cases.

task-5079559

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