affected versions: 16, 17

The query for `_sdd_get_usable_mandate` is far from optimal.

An EXPLAIN ANALYZE shows some pain points that we address in this PR: https://explain.dalibo.com/plan/c4eddda16fa4cf39

- Indexing `sdd_mandate` in `account.move` lets the subquery use an Index Scan instead of a full-table Seq Scan.
- Without changing the logic of the subquery it is now way more performant using NOT EXISTS, which avoids the Aggregate node and enables early exit.

These two minor changes yield a ~10x speedup in our tests.

(probably there's more performance to gain, although this seems to be an issue that will cease on later versions)


Some captures on performance over ~2000 payments. Before, a big chunk of the time was spent retrieving the mandate. The more operations the larger the time:

<img width="1246" height="655" alt="image" src="https://github.com/user-attachments/assets/3b6695e1-dbb0-46fa-a22c-fba0e9c2ec2b" />

Now over the same amount of payments, the mandates retrievement isn't that troubling anymore:

<img width="1050" height="609" alt="image" src="https://github.com/user-attachments/assets/63ad88d1-51a0-4607-ae50-8022cf4cffc7" />


cc @moduon MT-11292

fyi @yajo

Forward-Port-Of: odoo/enterprise#97410

Steps to Reproduce:
-------------------------
1. Create a PO with 2 PO lines.
2. On receipt, delete 1 move line.

Observation:
-------------------------
1. No user error is raised.

Issue:
-------------------------
When deleting a move from the receipt, if the move is not linked to any parent (`move_orig_ids`) or child (`move_dest_ids`) moves, the condition in the code evaluates to `False`. As a result, the `UserError` meant to prevent deletion is bypassed.
https://github.com/odoo/odoo/blob/ff1893a627fdde7cf752a0f6c19a02780cdf9774/addons/stock/models/stock_move.py#L1993-L1995

Solution:
-------------------------
1. When the unlink method is called internally (from the ORM side), pass a
specific context key (e.g. skip_state_check=True). Inside the
`_unlink_if_draft_or_cancel` method, use this context to bypass the state check.

2. When the user manually performs a delete operation (from the UI), no such
context will be passed. In that case, the state check will still apply, and a
`UserError` will be raised if the record is not in a valid state.

opw-5081681

This PR aims to fix issues introduced after the portal redesign.

task-3714408
part of task-3703251

- Requires https://github.com/odoo/enterprise/pull/55519

-----------

## Overflowing sidebar

With the portal redesign, we now use a two columns layout with a `d-inline-block` on the left one (sidebar), which allows the sidebar column to grow depending on its content.

While this brought more fluidity to the layout, it also introduced an issue, having a very long amount would make the sidebar overflow on the right column.

## Missing padding-bottom on container

Commit[1] removed a `padding-bottom` class from the container in order to reduce the vertical whitespace, but this introduced an issue in some cases, depending on the footer in use. By removing the `padding-bottom` utility class, the content of the customer portal would sometimes stick to the footer of the page.

## View timesheet button display

Depending on the sidebar layout, the View timesheet button will be display next to two other buttons, and with a `btn-link` class. We adapt the styling and position of the button to make it consistent with other views in which it is also displayed. 


## Alerts

While fixing the sidebar issue, this PR also fix some inconsistencies in the alerts used within Portal. Mainly about text alignment, and alerts with a link that were missing an `alert-link` class.