Description:
-----------
When viewing planning shifts in the gantt view, the total hours column displayed wrong totals due to timezone
misalignment in work interval calculations.

Steps to reproduce:
-------------------
1. Create an employee with a fixed working schedule (e.g., 8am-12pm, 1pm-5pm with 1-hour lunch break)
2. Ensure the employee's timezone differs from UTC (e.g., Europe/Brussels UTC+1)
3. Create a shift for this employee covering their full working day (8am-5pm)
4. Open the planning gantt view and check the total hours column for that day
5. Expected: 8 hours total | Actual: 7 hours total (with hours misaligned by timezone offset)

Root Cause:
-----------
In version 19.0, `_gantt_progress_bar_resource_id` used `.replace(tzinfo=pytz.UTC)` when building work intervals, which only changes the timezone label without converting the actual time values. This caused a timezone offset mismatch in the frontend's hour-by-hour comparison.

Solution:
---------
Replace `.replace(tzinfo=pytz.UTC)` with `.astimezone(pytz.UTC)` to properly convert datetime values to UTC before sending to the frontend.

opw-5190244

## Short functional explanation of the error
When setting a shift spread on multiple days for an employee who has a flexible schedule and previewing the planning of this employee, on the shown calendar, the color dot doesn't show. Instead, 'null' appears.

## Reproduction Steps
1. Go to planning and create a shift extended on multiple days for an employee who has a flexible schedule.
2. Click Publish and Send.
3. Click on Actions on the left top side and click Preview.
4. Select the employee you just created the shift for.
5. Click on Preview.
6. It opens a window with the employee's planning. On the left top side, click Month.

### Expected behavior
A shift spread on multiple days should show, with a color dot on the left of the schedule.

### Unexpected behavior
Null appears instead of the color dot. Moreover, the background of the shift has the color of the color dot that should be there.

## Origin of the issue
For employees with specified working schedules, multiple-days shifts are limited to their schedule. Thus, these shifts are split on the working hours of the employee.
But flexible employees have no specified working hours, so the shifts aren't split. This creates multiple day slots. FullCalendar generates different html codes for such slots, which don't contain class ```fc-daygrid-event-dot```, responsible for the creation of the color dot next to the shift schedule. However, even if this color dot isn't created, we still mention it here:
https://github.com/odoo/enterprise/blob/59cec3e8c6a0880178aa93651dca66c367d36841/planning/static/src/js/planning_calendar_front.js#L116 to display shifts. Therefore, we have to create it if it doesn't exist.
__
opw-5437257

1. Create a contact (with minimal details).
2. Create a customer invoice for that contact **last month** with `quantity = 300`.
3. Create a credit note for that invoice **this month**.
4. Create another customer invoice for the same contact **this month** with `quantity = 100`.

In the FAIA report (XML), within the General Ledger section, the partner is incorrectly classified as a supplier instead of a customer.

In the method _saft_fill_report_partner_ledger_values from account_saft, he partner type is determined based on whether the balance is negative.

However, a negative balance can result from a credit note, where the partner is still a customer and not a supplier. Furthermore, a partner can be both a supplier and a customer.

This commit allows a partner to be both a customer and a supplier. If both receivable and payable are 0 we set the partner type to customer to keep the behavior from e9640caf29e967fe7d8c6fe303b5a8d7a866437e

opw-5360924

Forward-Port-Of: odoo/enterprise#106315
Forward-Port-Of: odoo/enterprise#100749