gh-138122: Integrate live profiler TUI with _colorize theming system

[pablogsal]

The Tachyon profiler's curses-based TUI now uses the centralized theming
infrastructure in _colorize.py, enabling users to customize colors via
the standard Python theming API. This adds a LiveProfiler theme section
with two pre-configured themes: the default dark theme optimized for
dark terminal backgrounds, and LiveProfilerLight for white/light
backgrounds. Users can switch themes by calling _colorize.set_theme() in
their PYTHONSTARTUP or sitecustomize.py.

The table header rendering was also improved to draw a continuous
background, eliminating visual gaps between columns when using reverse
video styling.

• Issue: Implement PEP 799 – A dedicated profiling package for organizing Python profiling tools #138122

[picnixz]

Users can switch themes by calling _colorize.set_theme() in their PYTHONSTARTUP or sitecustomize.py.

I thought that this wasn't yet ready for public interface? should we really advertise this feature in the NEWS (cc @hugovk)

[pablogsal]

Users can switch themes by calling _colorize.set_theme() in their PYTHONSTARTUP or sitecustomize.py.

I thought that this wasn't yet ready for public interface? should we really advertise this feature in the NEWS (cc @hugovk)

Is not but eventually that will be the mechanism. I can change the news entry if you want

[picnixz]

Originally, I preferred not advertising this interface officially for now otherwise users could assume that they can freely use it as they want (and we don't know how we eventually want to document and expose it) but I saw that we had other NEWS entries that mentioned _colorize so... maybe just say that changing this should be at their own risk?

[hugovk]

Yep, hopefully we'll have something public for 3.15. In the meantime we could say experimental.

[pablogsal]

Fixed merge conflicts

[pablogsal]

I think everything should be addressed by now.

[picnixz]

LGTM. I like the mention about "experimental API" but this also makes me wonder whether we should have some "Experimental" section. Do we have APIs in mind that are experimental except _colorize? (C++ had, for a very long time, only experimental::filesystem as an experimental namespace, so having only 1 component in an experimental section would still makes sense IMO).

[pablogsal]

Do we have APIs in mind that are experimental except _colorize?

That's pending for @hugovk and @ambv. My understanding is that they plan to expose something in 3.15

[pablogsal]

Thanks for the review @picnixz ❤️