**Description of the issue/feature this PR addresses:**

When using the POS in dark mode, certain form control elements display
black text on a dark background, making them illegible.

This occurred because the POS application lacked the `color-scheme` CSS
property. While the backend web client correctly applied this property,
its absence in the POS meant the browser still assumed a light theme, 
forcing default User Agent styles (black text) onto native form controls 
that escaped standard view helpers.

This commit resolves the issue by applying the `$o-webclient-color-scheme`
variable to the POS application. This signals the browser to render form
controls and UI elements based on the current web client color scheme,
ensuring text remains legible within the POS app.

**Steps to reproduce:**

- POS > Open Restaurant Register
  - Hamburger icon (top right) > Switch to Dark Mode
  - Register > vertical ellipses icon (bottom left) > Quotation/Order > type in the search bar > observe black text on dark grey background


**Current behavior before PR:**

<img width="1911" height="588" alt="Before 1" src="https://github.com/user-attachments/assets/99581745-23eb-45e1-96f7-bca78853369c" />
<img width="1919" height="550" alt="Before 2" src="https://github.com/user-attachments/assets/b7eb9726-e2d2-492b-ad2b-6c0cc6613bb8" />

**Desired behavior after PR is merged:**

<img width="1910" height="433" alt="After 1" src="https://github.com/user-attachments/assets/419b7a2a-234e-47c8-854e-22adf6a7c5c1" />
<img width="1915" height="513" alt="After 2" src="https://github.com/user-attachments/assets/8f1cf5c9-5ad1-4aac-9879-840d6d9d537e" />

opw-6508945

### Description of the issue/feature this PR addresses:
Fixes an issue where timesheets lose their invoice reference when reversing and re-creating an invoice via a credit note.

### Current behavior before PR:
When reversing an invoice tied to timesheets and creating a replacement via a credit note, the timesheets linked to the original invoice have their timesheet_invoice_id cleared. Because the modify_moves function builds the replacement invoice directly via copy_data()/create(), it bypasses the normal sale order invoicing flow. As a result, the unbilled timesheets are left permanently unlinked from the newly created invoice, leaving the new invoice with no reference to the timesheets linked to the original sale order.

### Desired behavior after PR is merged:
When a replacement invoice is created, each timesheet is properly relinked to the corresponding line on the new invoice. This linkage matches on the sale order line (so_line) rather than line position, ensuring accuracy since line order and count are not guaranteed to be preserved between the original and modified invoices.

opw-6449995

---
I confirm I have signed the CLA and read the PR guidelines at www.odoo.com/submit-pr

Forward-Port-Of: odoo/odoo#283104

Step to reproduce:
 - create a faulty token that won't work and link it to a subscription
 - launch the recurring invoice cron
 - the following traceback occurs

```
last_tx_sudo = (self.transaction_ids - existing_transactions).sudo()
```

When the payment fails, the system rollback and we store the last_tx_sudo value in a dedicated variable. After rollback, the record does not exists anymore. Therefore, accessing the value fails.

```
  File "/home/odoo/src/enterprise/saas-18.2/sale_subscription/models/sale_order.py", line 1703, in _handle_automatic_invoices
    if not last_tx_sudo or last_tx_sudo.renewal_state in ['pending', 'authorized']:
                           ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/odoo/src/odoo/saas-18.2/odoo/orm/fields.py", line 1439, in __get__
    self.compute_value(record)
  File "/home/odoo/src/odoo/saas-18.2/odoo/orm/fields.py", line 1603, in compute_value
    records._compute_field_value(self)
  File "/home/odoo/src/odoo/saas-18.2/odoo/orm/models.py", line 4575, in _compute_field_value
    determine(field.compute, self)
  File "/home/odoo/src/odoo/saas-18.2/odoo/orm/fields.py", line 69, in determine
    return needle(*args)
           ^^^^^^^^^^^^^
  File "/home/odoo/src/enterprise/saas-18.2/sale_subscription/models/payment_transaction.py", line 25, in _compute_renewal_state
    if tx.state in ['draft', 'pending']:
       ^^^^^^^^
  File "/home/odoo/src/odoo/saas-18.2/odoo/orm/fields.py", line 1406, in __get__
    raise MissingError("\n".join([
odoo.exceptions.MissingError: Record does not exist or has been deleted.
```

Moreover, since https://github.com/odoo/enterprise/pull/45236/files#diff-c36fd7952cc2bef40716419a668de41963d49e1aa4177d9319d503fc260da588R1678-R1682

```
if not last_tx_sudo or not last_tx_sudo.renewal_state not in ['pending', 'authorized']:
```

has become

```
if not last_tx_sudo or last_tx_sudo.renewal_state in ['pending', 'authorized']:
```

But it feels strange to unlink the invoice when the payment succeed.


This PR fixes it.

Forward-Port-Of: odoo/enterprise#83913