Had to rework FontLoader because if NIXOS_LOGOTYPE_FONT_FILE was not set
then python would error when trying to load DimensionedLambda or
DimensionedLogomark

move many defaults to core.py
switch many dataclasses to regular classes
instrument all the classes to work nicely

make BaseRenderable run the _init_canvas method
fixup all the other class init function so it runs properly

move make_axis_lines to Canvas
make _init_canvas for DimensionedLogomark
clean up scripts

clean up snowflake scripts; no more manual canvases
update hashes
make background generation, make_svg_background, part of Canvas
remove make_svg_background from all other classes except special cases
clean up Logomark to use make_svg and get rid of old draw functions

Changes the default dark/light blue slightly. The dark blue is now
exactly in the color palette and the light blue has the same lightness
and hue as one of the colors in the palette but lower chroma.

Add copy for color palettes.
Update color palette logic.

Updated color TOML data so tints are key-value pairs instead of arrays.
This will make it easier to pick a color by a key name rather than index
into a list.

Version of the branding guide lives in a file so it can be used by
derivations and the typst document without de-syncing.

Moves the color palette TOML file to its own directory and turns it into
a derivation so it can be consumed externally. Restructures the branding
guide to pull in the palette from the derivation.