Map/Console other UI : Fails to load on Python 3.14

Apparently this is due to Python 3.14's tightened requirements for how it spawns new processes.

```
MANUAL> module load map
MANUAL> ERROR in command ['load', 'map']: module '__main__' has no attribute '__spec__'
Traceback (most recent call last):
File "/home/andre/.local/lib/python3.14/site-packages/MAVProxy-1.8.74-py3.14.egg/EGG-INFO/scripts/mavproxy.py", line 826, in process_stdin
File "/home/andre/.local/lib/python3.14/site-packages/MAVProxy-1.8.74-py3.14.egg/EGG-INFO/scripts/mavproxy.py", line 624, in cmd_module
File "/home/andre/.local/lib/python3.14/site-packages/MAVProxy-1.8.74-py3.14.egg/EGG-INFO/scripts/mavproxy.py", line 388, in load_module
File "/home/andre/.local/lib/python3.14/site-packages/MAVProxy-1.8.74-py3.14.egg/MAVProxy/modules/mavproxy_map/__init__.py", line 1549, in init
return MapModule(mpstate)
File "/home/andre/.local/lib/python3.14/site-packages/MAVProxy-1.8.74-py3.14.egg/MAVProxy/modules/mavproxy_map/__init__.py", line 88, in __init__
self.map = mp_slipmap.MPSlipMap(service=service, elevation=elevation, title=title)
~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/andre/.local/lib/python3.14/site-packages/MAVProxy-1.8.74-py3.14.egg/MAVProxy/modules/mavproxy_map/mp_slipmap.py", line 65, in __init__
self.child.start()
~~~~~~~~~~~~~~~~^^
File "/usr/lib/python3.14/multiprocessing/process.py", line 121, in start
self._popen = self._Popen(self)
~~~~~~~~~~~^^^^^^
File "/usr/lib/python3.14/multiprocessing/context.py", line 230, in _Popen
return _default_context.get_context().Process._Popen(process_obj)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^
File "/usr/lib/python3.14/multiprocessing/context.py", line 306, in _Popen
return Popen(process_obj)
File "/usr/lib/python3.14/multiprocessing/popen_forkserver.py", line 35, in __init__
super().__init__(process_obj)
~~~~~~~~~~~~~~~~^^^^^^^^^^^^^
File "/usr/lib/python3.14/multiprocessing/popen_fork.py", line 20, in __init__
self._launch(process_obj)
~~~~~~~~~~~~^^^^^^^^^^^^^
File "/usr/lib/python3.14/multiprocessing/popen_forkserver.py", line 42, in _launch
prep_data = spawn.get_preparation_data(process_obj._name)
File "/usr/lib/python3.14/multiprocessing/spawn.py", line 193, in get_preparation_data
main_mod_name = getattr(main_module.__spec__, "name", None)
^^^^^^^^^^^^^^^^^^^^
AttributeError: module '__main__' has no attribute '__spec__'. Did you mean: '__doc__'?
'MapModule' object has no attribute 'default_popup'
Traceback (most recent call last):
File "/home/andre/.local/lib/python3.14/site-packages/MAVProxy-1.8.74-py3.14.egg/EGG-INFO/scripts/mavproxy.py", line 1102, in periodic_tasks
File "/home/andre/.local/lib/python3.14/site-packages/MAVProxy-1.8.74-py3.14.egg/MAVProxy/modules/mavproxy_wp.py", line 124, in idle_task
super(WPModule, self).idle_task()
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^
File "/home/andre/.local/lib/python3.14/site-packages/MAVProxy-1.8.74-py3.14.egg/MAVProxy/modules/lib/mission_item_protocol.py", line 312, in idle_task
self.idle_task_add_menu_items()
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^
File "/home/andre/.local/lib/python3.14/site-packages/MAVProxy-1.8.74-py3.14.egg/MAVProxy/modules/lib/mission_item_protocol.py", line 331, in idle_task_add_menu_items
self.module('map').add_menu(self.menu)
~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^
File "/home/andre/.local/lib/python3.14/site-packages/MAVProxy-1.8.74-py3.14.egg/MAVProxy/modules/mavproxy_map/__init__.py", line 165, in add_menu
self.default_popup.add(menu)
^^^^^^^^^^^^^^^^^^
AttributeError: 'MapModule' object has no attribute 'default_popup'

```

Start with MAVProxy/modules/mavproxy_map/mp_slipmap.py at MPSlipMap.__init__, especially self.child.start(), and reproduce loading the map module under Python 3.14. Trace the multiprocessing child setup and verify that map initialization completes without the __main__.__spec__ or default_popup errors.

Written by the indexing model from the issue text.