# Steps to reproduce:
* Install **Accounting** and **l10n_be_reports**.
* Enable **debug mode**.
* Go to **Accounting → Reporting → Belgium → Partner VAT Listing**.
* Create invoices with invoice lines with no product set on it, just a label, so that **more than 10 Belgian partners** appear in the report and ensure each partner has a **VAT number**.
* Open the report **Options** tab and set **Load More Limit** to **5**.
* Click **Load More** until all partners are visible.
* Click **Returns** and create a return for the month you have created invoices for, and submit it.
* Download the generated XML.

# Observed behavior:
* The XML file contains only the first batch of partners.
* Partners shown after clicking **Load More** are missing from the export.

# Cause:
* In v17, the XML export button was defined as:
https://github.com/odoo/enterprise/blob/42ef1fe589fc4e7fe4b611736253251c44506578/l10n_be_reports/models/partner_vat_listing.py#L53-L59
* This meant clicking the button would go through the [export_file](https://github.com/odoo/enterprise/blob/42ef1fe589fc4e7fe4b611736253251c44506578/account_reports/models/account_report.py#L4927)
 method, which sets `options['export_mode'] = 'file'` before calling the export function. The test in v17 explicitly sets `export_mode = 'file'` to simulate what `export_file` does in production.
 
* In v19, the architecture changed:
  - The XML export is now triggered via the account.return workflow and a submission wizard [1.](https://github.com/odoo/enterprise/blob/19.0/l10n_be_reports/wizard/vat_listing_submission_wizard.py)
  - The wizard's `print_xml` method calls [_get_closing_report_options()](https://github.com/odoo/enterprise/blob/19.0/account_reports/models/account_return.py#L1601) which does NOT set `export_mode = 'file'`.
  - The controller then calls `dispatch_report_action(options, file_generator)` directly, bypassing `export_file`.
 
* Why the test changed:
  - In v17 test: `export_mode = 'file'` was set to mimic the `export_file` →  `partner_vat_listing_export_to_xml` flow.
  - In v19 test: `export_mode = 'file'` should NOT be needed in the test because the fix is to set `export_mode = 'file'` inside `partner_vat_listing_export_to_xml` itself.


# Fix:
* Enable **export mode** when generating the XML.
* Ensures all partners are included regardless of the load limit.

opw-5494247

### Issue:
When exporting Modelo 390 reports for a past year, the BOE file was empty — all values were 0

### Cause:
In `export_boe()`, the `report_lines` were get based on the `section_report` options
However, `section_reports` do not store the date
or return periodicity of the selected report
As a result, using their options always fetched data for the current period instead of the specified year

### Note:
`_generate_mod_390_page2()` also had issues:
some lines were missing or incorrectly indexed

The mod 360 format, it strict in the structure with specific index so it may produce invalid documents

The latest documentation for mod 390:
https://sede.agenciatributaria.gob.es/static_files/Sede/Disenyo_registro/DR_300_399/archivos_25/dr390e2025.xlsx

### Steps to reproduce:
- Install `l10n_es_reports` and switch to ES Company
- Create an Invoice and a Bill (Any product, Price: 100.00, Tax: 21%, Invoice Date: 01/01/2025)
- Open Tax Return, switch to Mod 390, and set year to 2025
- You should see data in the 2 first sections
- Use the gear icon, and download the BOE
- Use the gear icon to download the BOE, fill the wizard (Natural Person – Name: Test, Principal activity: Test, Activity Code: 12345), and generate the file Before the fix: all values in the BOE were 0 instead of matching the report

opw-5457374

Forward-Port-Of: odoo/enterprise#106676
Forward-Port-Of: odoo/enterprise#104928

Link to Avalara (Avatax) documentation:
https://developer.avalara.com/api-reference/avatax/rest/v2/models/LineItemModel/

Expected Behaviour:
The itemCode sent to the AvaTax API should be 50 characters or fewer
to comply with Avalara's field length constraints.

Actual Behaviour before the Fix:
When an itemCode exceeded 50 characters, the system attempted to send
the request as-is. This resulted in the AvaTax API returning an error,
causing the transaction or tax calculation to fail.

Behaviour with the Fix:
The system now ensures that the itemCode adheres to the 50-character
limit before the API call is made, by trancating the code to the
first 50 characters if it exceeds 50 characters. This prevents API
rejection and ensures successful tax processing for items with
long identifiers.

Steps to reproduce:
1. Create or select a product/item with a reference (or barcode if
   using UPC) longer than 50 characters.
2. Trigger an action that calculates tax via the AvaTax
   integration (e.g., creating an invoice or updating a line item).
3. Observe the API response.

- Before fix: API returns a validation error regarding the
  itemCode length.
- After fix: Request is successful as the itemCode is
  properly handled/validated.

opw-5406451

Forward-Port-Of: odoo/enterprise#106085
Forward-Port-Of: odoo/enterprise#105017