Accepted busy calendar meetings now automatically create planning slots, so managers can see when employees are unavailable without checking Calendar separately. This helps avoid assigning shifts that conflict with meetings and keeps planned working time reports more accurate.

PURPOSE
=======

Currently, if an employee is already booked for a meeting, this is not
displayed in Planning. Therefore, their manager can still schedule them
some shifts, which they won't be able to attend because they are already busy
elsewhere. This means that they have to contact their manager and the latter
has to make the necessary adjustements afterwards, which is a headache.

The manager can still open the Calendar app on another screen and
double-check the availabilities of the employee before scheduling
anything, but that's not practical. In addition, it would skew the
reporting as it would appear that the employee hasn't been assigned
enough hours, when it is the case.

SPECS
=====

When a `calendar.event` is created, a `planning.slot` is automatically
generated when:
 - the event visibility (`show_as`) is set to `busy`;
 - the attendee has accepted the invite.

The `Meeting` role cannot be edited (but its color) nor deleted as it's
the default one assigned.

TaskID: 2581479

Users can now generate the planning schedule as a PDF, making it easier to print and share around the office. The same PDF is also attached automatically when sending planning emails, helping recipients keep a portable copy.

Generate the planning by PDF, so it can easily printed to be shown
around in the office, etc.

The planning is also attached to the email sent by the "Send Planning"
wizard.

TaskID: 2271395

When users add a timesheet line while viewing a different week, the default date now matches the displayed period instead of incorrectly using the current weekday. This helps prevent entries from being created on the wrong date and reduces manual corrections.

Currently, the date set by default is the current day of the week
but on the period displayed.

step to reproduce:-
go to timesheets > my timesheets >
go to another week than the current one > add a line

After this commit, except for the current week, the date set by default
should be the first working day of the period displayed.

Task-Id:2585241
PR: #21538

Currently in 15.0, while an employee is on leave, the timesheet app considers it as overtime and due to that, it shows extra worked hours. In actuality, the employee was on leave. So in this commit, When employees put leaves than the Timesheet consider it as leaves rather than overtime. task-263559 Forward-Port-Of: odoo/enterprise#21918

Currently in 15.0, while an employee is on leave, the timesheet app
considers it as overtime and due to that, it shows extra worked hours.
In actuality, the employee was on leave.

So in this commit, When employees put leaves than the Timesheet
consider it as leaves rather than overtime.

task-263559

Forward-Port-Of: odoo/enterprise#21918