Importing attendees on an event that has an `after_sub` mail scheduler (the default on every event) fails with `savepoint "..." does not exist` and the import is aborted.

[`_update_mail_schedulers`](https://github.com/odoo/odoo/blob/b2f3270271f6/addons/event/models/event_registration.py#L298) runs the attendee scheduler synchronously on every registration create. The scheduler commits after each mail batch, which is fine from cron but problematic during an import: since [29460b723f49](https://github.com/odoo/odoo/commit/29460b723f49) [`load`](https://github.com/odoo/odoo/blob/b2f3270271f6/odoo/orm/models.py#L884) uses a single savepoint for the whole run, and any commit underneath releases it, so the next `ROLLBACK TO` / `RELEASE SAVEPOINT` raises `InvalidSavepointSpecification`.

When `import_file` is in context, trigger the cron like the async path already does so the mails are queued instead of running inline.

Steps to reproduce:

0. Have Contacts and Events installed
1. Events > Events, create a published event
2. Open the event, Attendees tab > Favorites > Import records
3. Upload a file with new attendees (Name, Email, no external id)
4. Click Import

=> "savepoint ... does not exist", import fails

Ticket [link](https://www.odoo.com/odoo/project.task/6124741)
opw-6124741

Forward-Port-Of: odoo/odoo#260648

Currently, an error occurs when the user receives a dropship order instead of delivering it directly to the customer. As a result, the sale order shows a negative delivered quantity.

## Steps to replicate:
- Install Sales, Inventory, and Purchase.
- Enable Dropshipping from Inventory settings.
- Create a test product with the Dropship route enabled and set a vendor for it in the Purchase tab.
- Create and confirm a quotation for a customer.
- Go to Purchase > `Deliver To:` and set it to `My Company: Receipts.`
- Confirm the Purchase Order and validate the receipt.
- Go back to the Sale Order.

## Observed Behavior:
The delivered quantity is -1, which is incorrect because the customer has not returned any products, nor has the user created a sale order line with a negative quantity (which would indicate a return).

## Root cause:
When computing the delivered quantity at [1], the function `_get_outgoing_incoming_moves` [2] is called to retrieve the incoming and outgoing stock moves associated with the sale order lines.

Inside this function, moves are filtered and categorized as incoming or outgoing. At [3], the condition is satisfied because the default value of `to_refund` is `True`, so the move is added to `incoming_move_ids`. Later, during the computation at [1], the code iterates through the incoming moves and subtracts their quantities from the delivered quantity.

Since the initial delivered quantity is 0, including such a move in `incoming_move_ids` causes the delivered quantity to become -1.


<h3> Why did this behavior not occur in lower versions?:</h3>

This issue was introduced by [commit], which added the functionality for users to return products that are not listed in the purchase order. As a result, their quantities appear as negative received quantities on the purchase order.

Before this change (in saas-18.2), the field `move.to_refund` had a default value of `False`. Because of this, the condition at [3] was not satisfied, and the move was not included in `incoming_move_ids`. Therefore, it was not subtracted when iterating through incoming moves, and the delivered quantity did not become negative.

Starting from 18.3, the default value of `to_refund` was changed to `True`. This causes the condition at [3] to be satisfied, the move to be included in `incoming_move_ids`, and its quantity to be subtracted during the computation, resulting in a delivered quantity of -1.

[1]-
https://github.com/odoo/odoo/blob/1256875226436a854558a1334ffdc886fa4767a8/addons/sale_stock/models/sale_order_line.py#L193-L209 
[2]-
https://github.com/odoo/odoo/blob/1256875226436a854558a1334ffdc886fa4767a8/addons/sale_stock/models/sale_order_line.py#L316-L353 
[3]-
https://github.com/odoo/odoo/blob/1256875226436a854558a1334ffdc886fa4767a8/addons/sale_stock/models/sale_order_line.py#L346-L351

## Solution:
We can make the condition stricter by ensuring that only incoming moves that are actual returns are counted as negative in the quantity delivered on a sale order. 

Specifically, if an incoming move has no corresponding originating return move and the customer has not created a sale order line with a negative quantity (which could also indicate a return), it should not be considered when calculating the delivered quantity.

[commit]:
https://github.com/odoo/odoo/pull/209110/changes/c1c86182e4b28e929bf56e79f57f33aaa13e67f1

opw-5933594

Forward-Port-Of: odoo/odoo#252383

**Steps to reproduce:**
1. Install l10n_es_edi_verifactu.
2. Switch to a ES company.
3. Create a customer invoice and send it to VeriFactu.
4. Enable Developer Mode.
5. Go to Settings > Technical > Sequences & Identifiers > Sequences.
6. Search for the `Sequence Code: l10n_es_edi_verifactu` and open it.
7. Set a prefix or suffix using any alphabetical character.
8. Create a new invoice and send it to VeriFactu

**Issue:**
Traceback on sending Veri*Factu:
`ValueError: invalid literal for int() with base 10: 'F260001'`

**Cause:**
The value returned by `ir.sequence.next_by_id()` may contain alphabetical characters (due to prefix/suffix), while the field `chain_index` expects an integer. The raw sequence value was directly assigned, causing the conversion to fail.

**Fix:**
Catch the ValueError raised by int() when the sequence value contains non-numeric characters (e.g. due to a prefix/suffix). Instead of crashing, surface a user-friendly error on the document telling the user to remove the prefix/suffix from the sequence configuration.

**opw-6037528**

Forward-Port-Of: odoo/odoo#255473

### Issue:
When the company `tax_periodicity` is set to quarterly, the generated SII invoice JSON still uses the monthly period format

According to the documentation, the options for Periodo include distinction between monthly and trimester (p224 - 225):
https://sede.agenciatributaria.gob.es/static_files/Sede/Procedimiento_ayuda/G417/FicherosSuministros/V_1_1/SII-Descripcion-ServicioWeb-v1-1_es_es.pdf

### Cause:
The invoice JSON generation does not consider the company's `tax_periodicity`

This logic was probably omitted because `account_reports` may not be installed
However, when the periodicity is configured, the generated SII document should reflect it correctly

### Steps to reproduce:
- Install `l10n_es_edi_sii` and `account_reports`
- In Settings, set `Tax Periodicity` to `Quarterly`
- In Settings, set `Tax Agency for SII` to `Agencia Tributaria Española`
- Change ES Company vat number to `ESA12345674`
- Create an invoice (Date: 01/05/2026, Customer: ES Company)
- Open the generated JSON document
- Check the Periodo value, it should be 2T in May

opw-6050587

Forward-Port-Of: odoo/odoo#267557
Forward-Port-Of: odoo/odoo#264063

If expanding a line in the General Ledger report using a prefix group (defined on `prefix_groups_threshold`) users experience a crash due to a bad domain.

This bad domain is caused by a custom groupby key that is not a real field name, which causes the invalid domain name to be generated here https://github.com/odoo/enterprise/blob/e9a920d62a5894d8198fdbf2e35032de555d0bd7/account_reports/models/account_report.py#L5895-L5898

The solution adds mapping of the groupby names to the actual field names and adjusts `_report_expand_unfoldable_line_groupby_prefix_group()` to read the custom groupby keys from this mapping, thus creating valid domains.

This also changes the `forced_domain` to use `display_name` instead of `name` , allowing the lines to expand properly. https://github.com/odoo/enterprise/blob/da6ab7eedfa1b326cc6e01876dfff30e50a1c578/account_reports/models/account_report.py#L5896

Reproduction steps:
Runbot 18.4
Debug/Developer mode
Accounting -> General Ledger Report
Gear icon in top bar
Options -> Lower the prefix_groups_threshold to 1
Go back to the general ledger, try expanding some lines and see crash

**Only affects 18.4**

opw-6231127