Dashboard: Wait for Inputs, Fix Python 3.14

[ax3l]

Try to fix CI by asking Cursor to fix it.

Wait for Inputs

Try to fix the failing Ubuntu test test_python_import.py::test_python_import saying

 Element {#lambdaX} was not visible after 10 seconds!

That one also passes on my local pc

Fix Python 3.14 (macOS CI)

Dashboard never started up:

      File "impactx/src/python/impactx/dashboard/start.py", line 45, in start
    server.start()
    
      File "/Library/Frameworks/Python.framework/Versions/3.14/lib/python3.14/site-packages/trame_server/core.py", line 716, in start
        task = CoreServer.server_start(
    ...
    
      File "/Library/Frameworks/Python.framework/Versions/3.14/lib/python3.14/site-packages/wslink/protocol.py", line 33, in __init__
        self._completion = asyncio.get_event_loop().create_future()
                           ~~~~~~~~~~~~~~~~~~~~~~^^
      File "/Library/Frameworks/Python.framework/Versions/3.14/lib/python3.14/asyncio/events.py", line 715, in get_event_loop
        raise RuntimeError('There is no current event loop in thread %r.'
                           % threading.current_thread().name)
    RuntimeError: There is no current event loop in thread 'MainThread'.

[ax3l]

Fixed via #1208