## Description

When loading demo data from **Settings** after installing `l10n_in` without demo data, the `_install_demo` method receives company IDs instead of a `res.company` recordset.

As a result, the following line crashes:

```python
companies.filtered(...)
```

with:

```text
AttributeError: 'int' object has no attribute 'filtered'
```

This PR ensures that the received company IDs are converted into a `res.company` recordset before being processed, allowing demo data to be loaded successfully from the Settings menu.

## Steps to Reproduce

1. Install `l10n_in` **without demo data**.
2. Navigate to **Settings**.
3. Click **Load Demo Data**.

## Current Behavior

Demo data installation fails with:

```text
AttributeError: 'int' object has no attribute 'filtered'
```

## Expected Behavior

Demo data should be installed successfully without raising any exception.

## Solution

Convert the received company IDs into a `res.company` recordset when the argument passed to `_install_demo` is not already a recordset.

Currently, an error occurs when a user sorts tasks by Planned Date.

**Steps to reproduce:**
 - Install the `project_enterprise` module with demo data.
 - Go to Projects in the portal (`/my/projects`), open any `project`, and sort the 
   tasks by `Planned Date`.

KeyError: 'order'

After a [recent change], the sort order is retrieved from searchbar sortings. When sorting by 
Planned Date, it attempts to access the order key from the corresponding sorting configuration [1]. 
However, the planned_date_begin entry does not define an order key [2], which raises 
error when it tries to access order.

This commit ensures that the order key is added with its value for planned_date_begin in 
searchbar sorting.

[recent change]: https://github.com/odoo/odoo/commit/8be5dacf9fbfe8c23b04c876994bea2ce7cbb89a

[1]: https://github.com/odoo/odoo/blob/2ae9b57b86cd0bc4816ff8ec207564631baa8ad6/addons/project/controllers/portal.py#L424

[2]- https://github.com/odoo/enterprise/blob/9dd3a9b2c09a6d23a3f71d3e531edd6d78b30277/project_enterprise/controllers/portal.py#L8-L11

sentry-7556050938

## Issue
In the *Data Recycle* app, when grouping records, the record IDs are summed up and appear right next to the name of each group, which:

1. truncates the name and count of the groups
2. does not make sense (summing up IDs is pointless)

<img width="720" height="281" alt="115492" src="https://github.com/user-attachments/assets/567902af-b356-4a0a-8b1e-2ed101a2eba3" />

## Steps to reproduce
1. Install *Data Recycle* (`data_recycle`)
2. In Data Cleaning > Configuration > Recycle Records, create a new rule:
    - Any name
    - Model: *Contact*
    - Filter: *Name contains G* (or anything else that matches some records)
4. Click the *Run Now* button in the upper left corner
5. In Data Cleaning > Recyle Records, group the records by any field (e.g., *Model*)
6. **The name of the group (Contact) is truncated, making it and the record count unreadable. This is due to the sum of Record ID being displayed in the same row, even though that information is irrelevant.**

## Cause
Similarly to related enterprise PR https://github.com/odoo/enterprise/pull/115492, the *Record ID* field of the `data_recycle.record` model uses the default `sum` aggregator.

https://github.com/odoo/odoo/blob/6de867f1c92bacedc0574b63e9e6a2a57fe805dd/addons/data_recycle/models/data_recycle_record.py#L17

related: https://github.com/odoo/enterprise/pull/115492

opw-6219824

Forward-Port-Of: odoo/odoo#265163

## Issue
In the *Data Cleaning* app, when grouping records, the record IDs are summed up and appear right next to the name of each group, which:
1. truncates the name and count of the groups
2. does not make sense (summing up IDs is pointless)

<img width="709" height="374" alt="6166623-before" src="https://github.com/user-attachments/assets/9d80b1ec-49c0-4b7f-8c6e-53846f9e433e" />

## Steps to reproduce
1. Install *Data Cleaning* (`data_cleaning`)
2. In Data Cleaning > Configuration > Field Cleaning, create a new rule (or edit an existing one):
    - Any name
    - Model: *Contact*
    - Rule:
        - Field to Clean: *Name (Contact)*
        - Action: *Set Type Case* - Case: *All Uppercase*
4. Click the *Clean* button in the upper left corner
5. In Data Cleaning > Field Cleaning, group the records by any field (e.g., *Field*)
6. **The name of the group (_Name (Contact)_) is truncated, making it and the record count unreadable. This is due to the sum of _Record ID_ being displayed in the same row, even though that information is irrelevant.**

## Cause
The *Record ID* (`res_id`) field is an Integer field defined [here](https://github.com/odoo/enterprise/blob/3603afdd5c0d19c9276f3855156be4040ab5717d/data_cleaning/models/data_cleaning_record.py#L20). By default, Integer fields have the `sum` aggregator:

https://github.com/odoo/odoo/blob/681610c002a310f1c73fc2e5bec8d3dae27bc4a7/odoo/orm/fields_numeric.py#L17-L23

This causes the IDs to be summed up and appear in the group headers.

## After

<img width="740" height="370" alt="6166623-after" src="https://github.com/user-attachments/assets/a42d8f58-06dc-4308-8b6f-1ab09e8034f8" />

related: https://github.com/odoo/odoo/pull/265163

opw-6166623

Forward-Port-Of: odoo/enterprise#115492

# How to reproduce
- Create an Event registration
- Add a follower
- Click on the enveloppe icon next to the sender's name in the chatter

# The problem
A traceback appears

# Cause of the issue
When clicking on the enveloppe, we display the `message_notification_popover` that calls `isFollowerNotification` to filter follower notifications from other ones. This function compares the ids of the followers of the notification to it's res_partner_id : https://github.com/odoo/odoo/blob/ee12a62407fa1c2dbca00d77dc6d5bd16eac1e43/addons/mail/static/src/core/common/notification_model.js#L101-L105

But in our case res_partner_id is undefined because it is not a required field and it will not be set in the case of mass_mailing :
https://github.com/odoo/odoo/blob/ee12a62407fa1c2dbca00d77dc6d5bd16eac1e43/addons/mail/models/mail_notification.py#L23-L27

opw-6178443

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Forward-Port-Of: odoo/odoo#265263

Steps to reproduce:
- Create a US company
- Go to Accounting > Configuration > Settings
- Activate `Avatax` > Set Credentials
- Try to "Sync Parameters"

Traceback:
```py
  File "/home/odoo/src/enterprise/saas-19.2/account_avatax/models/res_company.py", line 113, in avatax_sync_company_params
    'valid_country_ids': [(6, 0, get_countries(vals['validCountries']).ids)],
                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/odoo/src/enterprise/saas-19.2/account_avatax/models/res_company.py", line 90, in get_countries
    return self.env['res.country'].browse([country_cache[code] for code in code_list])
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/odoo/src/odoo/saas-19.2/odoo/orm/models.py", line 5208, in browse
    assert all(ids) or all(isinstance(x, NewId) or x for x in ids), "Invalid falsy real id"
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError: Invalid falsy real id
```

The issue occurs because AvaTax return `*` in the `validCountries` field to indicate that an exemption code is valid for all countries. The synchronization logic stores this value in the country cache as `False` and later passes it to `res.country.browse()`. Since `browse()` does not accept a mix of valid IDs and falsy values, the operation crashes during the synchronization process.

This commit filter out falsy country IDs when resolving country codes to prevent crashes and allow exemption codes to be synchronized successfully.

opw-6298189

Version:
- 19.0

Steps to reproduce:
- Create a sign template with a readonly sign item linked to an auto field.
- Use a reference record where the linked field value is empty or False.
- Send the document for signing.
- Complete the signing flow.

Issue:
- Readonly sign items linked to auto-filled values could not properly handle
  falsy values. Empty values could trigger the error "Some required items are
  not filled" and completed sign requests displayed the sign item placeholder
  instead of the actual auto-filled value.
- completed document generation could fail when rendering falsy values for
  textarea sign items.

Cause:
- Falsy auto-filled values were ignored during constant item population and
  replaced by the sign item placeholder. Additionally, readonly constant items
  were included in required field validation and completed sign requests
  continued to display placeholders when the stored value was empty.
- document rendering assumed sign item values were always strings for textarea
  sign items but when auto field is empty it value can be False.

Fix:
- Preserve falsy values when populating readonly constant items, exclude
  constant items from signer validation, and hide placeholders for empty
  auto-filled constant items when displaying completed sign requests.
- Normalize falsy values to prevent crashes and allow completed documents
  to be generated correctly.

Forward-Port-Of: odoo/enterprise#121009

This commit does not bring native support for EPD on credit notes, only makes custom support a little easier and cleaner.

It is quite easy to support EPD (early payment discounts) on refunds by extending
- `_early_payment_discount_move_types`
- `_is_eligible_for_early_payment_discount`

However, this approach breaks when it reaches `inverse_tax_rep` in `_get_invoice_counterpart_amls_for_early_payment_discount_per_payment_term_line`, which assumes tax repartition lines with `document_type == 'invoice'` and raises when called on `tax_rep` lines of 'refund' type instead.

This commit fixes that by selecting source and target repartition lines according to the `tax_rep`'s document type, which ensures:
- the `.index()` no longer raises a `ValueError`, as `tax_rep` is now looked up in the matching set (`refund_` for refunds, `invoice_` otherwise)
- `inverse_tax_rep` returns the corresponding line in the opposite set, preserving the original invoice->refund mapping while adding the refund->invoice one

Since `inverse_tax_rep` is a closure, downstream modules cannot patch it without copying the whole ~170-line method. Making it symmetric here lets custom EPD-on-refund support work without that duplication.

task-[6265601](https://www.odoo.com/odoo/all-tasks/6265601)

---
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Forward-Port-Of: odoo/odoo#271102