[REQUEST] WindowManager.add unexpected behvaiour with slot names

Is your feature request related to a problem? Please describe. Tl;dr: manager.add(..., assign="Console") turns the slot name to lowercase, unlike the add_slot "constructor", which is unintuitive.

I wanted to structure my app with a console at the bottom (like vscode's default), a main screen, and an inventory to the right. I couldn't find in the documentation how to structure my app's layout, but I found this example on reddit - https://www.reddit.com/r/Python/comments/uot805/detailing_pytermguis_brand_new_layout_system/, so I tried applying it to what I understood. I tried running the following code:

def main3():
    def macro_time(fmt: str) -> str:
        return time.strftime(fmt)

    ptg.tim.define("!time", macro_time)  # type: ignore
    with ptg.WindowManager() as manager:
        manager.layout.add_slot("Header", height=5)
        manager.layout.add_slot("Header Left", width=0.2)

        manager.layout.add_break()

        manager.layout.add_slot("Body", width=0.7)
        manager.layout.add_slot("Body Right")

        manager.layout.add_break()

        manager.layout.add_slot("Console", height=3)

        manager.add(
            ptg.Window("[bold]The current time is:[/]\n\n[!time 75]%c", box="EMPTY"),
            assign="Console",
        )

But it complained that there was no slot named Console:

  File "/usr/lib/python3.10/runpy.py", line 196, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "/usr/lib/python3.10/runpy.py", line 86, in _run_code
    exec(code, run_globals)
  File "/home/guy/projects/fl-fangame/fl_fangame/__main__.py", line 3, in <module>
    from fl_fangame.cli import main  # pragma: no cover
  File "/home/guy/projects/fl-fangame/fl_fangame/cli.py", line 10, in <module>
    main3()
  File "/home/guy/projects/fl-fangame/fl_fangame/window.py", line 80, in main3
    with ptg.WindowManager() as manager:
  File "/home/guy/projects/fl-fangame/venv/lib/python3.10/site-packages/pytermgui/window_manager/manager.py", line 121, in __exit__
    raise exception
  File "/home/guy/projects/fl-fangame/fl_fangame/window.py", line 93, in main3
    manager.add(
  File "/home/guy/projects/fl-fangame/venv/lib/python3.10/site-packages/pytermgui/window_manager/manager.py", line 227, in add
    getattr(self.layout, assign).content = window
  File "/home/guy/projects/fl-fangame/venv/lib/python3.10/site-packages/pytermgui/window_manager/layouts.py", line 391, in __getattr__
    raise AttributeError(f"Slot with name {attr!r} could not be found.")
AttributeError: Slot with name 'Console' could not be found.

Only by looking at the source (Layout's __getattr__) did I find that I had to pass it in lowercase - and not like how I passed the slot name when creating it.

In addition, it took me a while to find the assign argument - I didn't find it by ctrl-F ing "Layout" in the documentation, although in hindsight I could have found it by looking at the docstring

Describe the solution you'd like Assuming the features I tried to use aren't too low level:

The docs should have a section about how to use Layouts (I was heavily overwhelmed by the documentation)
Assigning to slots should be more intuitive: Either the slot name should be used in the same way in manager.add(..., assign=) and in add_slot, or you should have a Slot object you can call .add on, or pass it instead of the name to assign=
I think that renaming assign to slot would make it clearer - of course it's breaking, and thus probably not feasable.

If the layout feature is lower-level than what I needed, manager.layout should have a docstring warning of that.

There's a very good change I'm missing a lot of the reasons why the current state is good because of how it interacts with the rest of pytermgui, or because layouts aren't supposed to be used by users - but as a TUI beginner trying to jump in by doing, I came out very confused by them.

Describe alternatives you've considered I gave whatever alternatives I thought of in the above section

bczsalba / pytermgui

[REQUEST] WindowManager.add unexpected behvaiour with slot names #147