#### Issue:

- When an employee is assigned a resource calendar with the `flexible_hours` option enabled, the daily/weekly overtime on the timesheet calendar is not calculated based on the 'Average Hour per Day' that we set for the flexible resource, it is instead being calculated based on the specific work intervals.

#### Steps to reproduce:

1. Assign a resource calendar with `flexible_hours` enabled to an employee.
2. Ensure the calendar has a defined `hours_per_day` value.
3. Verify that the timesheet grid correctly shows the daily/weekly overtime hours as per `hours_per_day`.
4. Test with non-flexible schedules to confirm existing behavior remains unchanged.

#### Solution:
- In the frontend, the method `fetchDailyWorkingHours` retrieves daily working hours data by calling the backend method `get_daily_working_hours`.
- This method computes working hours based on the employee's `resource_calendar_id` and its associated work intervals. However, It does not check if the `flexible_hours` flag is enabled on the `resource_calendar_id`. For employees with flexible schedules, the backend still calculates working hours based on detailed intervals instead of simply using the `hours_per_day` value defined in the `resource_calendar`.
- To fix this I ensure we respect flexible schedules by using `hours_per_day` directly when `flexible_hours` is enabled.

opw-4407910

Forward-Port-Of: odoo/enterprise#77315

Follow-up of https://github.com/odoo/odoo/pull/176758

Commit above adds elligible partners in `@` mention suggestions, when the channel is restricted.

However, channel threads could mention anyone, which is unintended.

Steps to reproduce:
- open a restricted channel, e.g. `#general`
- open or make a sub-thread on this channel
- type `@` in composer

=> non-internal users are shows in suggestion list.

This happens because when the channel is restricted, this limits the amount of partners in the mention list. Problem is that channel threads do not set their `group_public_id`, and instead the parent value should be checked. This was not taken into account, which lead to unrestricted list of suggestions in these channels.

This commit fixes the issue by checking the parent channel `group_public_id` for listing the elligible people that can be mentioned.

Before
![Screenshot 2025-01-24 at 15 11 23](https://github.com/user-attachments/assets/fe4ff3ad-b223-439a-bf0a-61dd3a85523f)

After
![Screenshot 2025-01-24 at 15 10 50](https://github.com/user-attachments/assets/ac75d0af-d13b-4a5c-9b7d-aa7fe16c5792)