This prevents the state of initial color/text-align/line-width/etc to
be dependent on the state of the previous rendering call - presuming
further nested balanced save/restore pairs.

Slight adjustment of gradient stops to distribute primary colors better
on characters of flow3r. Use single precision constants rather than
double precision constants for coordinates.

This change makes st3m aware of what Micropython is doing, and lets st3m
provide some 'failsafe' functionality even if Micropython crashes.

Most notably, this lets us draw some useful messages when the badge is
in REPL mode, and lets us implement things like restarting the badge via
buttons if that happens.

This API isn't fully used yet, but this is a start.

This doesn't seem to be less performant than the rube goldberg we had
previously, but somehow fixes up rendering glitches.

Phew.

This was mostly blocked by Micropython, but it has since then also
upgraded to IDF 5: https://github.com/micropython/micropython/commit/e4650125b88a35f074097f16d84a8f49bd22ac06

We take that change and selectively apply it where necessary. However,
it's not a 1:1 patch apply, as we already were on a somewhat forked
Micropython, and we also want to support IDF 5.1, not 5.0.

We also bump up the IDF distribution brought in by Nix, and fix some
warnings that have since turned into errors due to toolchain changes.

This is an annoyingly large change, but the gist of it is that we:

1. Move ctx into components/ctx
2. Move uctx into usermodule/mp_uctx.c
3. Split out uctx config into ctx_config.h and share it with the
   simulator.
4. Delete a bunch of unused ctx files
5. Flip some ctx bits for speed.
6. Draw the rest of the owl, ie. implement a dedicated rasterizer task
   in components/st3m.

This implements the 'crtc' part of the graphics stack, ie. the task
responsible for blitting out a set of framebuffers over SPI as fast as
possible.

Currently this is still single-buffered, as the micropython API needs to
be changed to support injected, per-frame ctx instances.