Implement a new color system inspired from base24

[bjarneo]

Implement a new color system with inspiration from base24 (can't edit the title)

The goal of this PR is to provide users with more color options when theming their application.

This implementation is more or less base24, however, the base24 naming convention is hard to follow, so I renamed the colors to a sane naming convention.

This PR will also move btop theming to a template file. It will also break the current setup for others who have changed to the colors.toml, so if this is going into the core, I can either write a mapping from the current colors.toml to the new one, or a script to convert to this system.

To do: Verify the colors for all the themes

The previous closed PRs:
#4526
#4538

Based on this post, https://discord.com/channels/1390012484194275541/1399365674832232448/1469128896166494289
and a discussion regarding the btop colors before the colors.toml launch.

Color Reference

Mapping between Omarchy color names and Base24 identifiers.

Shade ramp

Name	Base24	ANSI
bg	base00	-
lighter_bg	base01	0
selection	base02	8
muted	base03	-
dark_fg	base04	-
fg	base05	-
light_fg	base06	7
bright_fg	base07	15

Accent colors

Name	Base24	ANSI
red	base08	1
yellow	base09	3
orange	base0A	-
green	base0B	2
cyan	base0C	6
blue	base0D	4
purple	base0E	5
brown	base0F	-

Extended colors

Name	Base24	ANSI
dark_bg	base10	-
darker_bg	base11	-
bright_red	base12	9
bright_yellow	base13	11
bright_green	base14	10
bright_cyan	base15	14
bright_blue	base16	12
bright_purple	base17	13

Semantic keys

These are set independently per theme and are not part of the Base24 spec:

Name	Purpose
background	Terminal/app background
foreground	Terminal/app foreground
accent	Primary accent color
cursor	Cursor color
selection_background	Selected text background
selection_foreground	Selected text foreground

Demo of Ayu Mirage

A test using base24 color scheme of Ayu Mirage, converted into the Omarchy colors

accent = "#73d0ff"
cursor = "#d9d7ce"
foreground = "#cccac2"
background = "#1f2430"
selection_foreground = "#d9d7ce"
selection_background = "#323844"

bg = "#1f2430"
lighter_bg = "#242936"
selection = "#323844"
muted = "#4A5059"
dark_fg = "#707a8c"
fg = "#cccac2"
light_fg = "#d9d7ce"
bright_fg = "#f3f4f5"

red = "#f28779"
yellow = "#ffad66"
orange = "#ffd173"
green = "#d5ff80"
cyan = "#95e6cb"
blue = "#73d0ff"
purple = "#d4bfff"
brown = "#f27983"
dark_bg = "#171b24"
darker_bg = "#1a1f29"
bright_red = "#ff6666"
bright_yellow = "#ffcc66"
bright_green = "#87d963"
bright_cyan = "#5ccfe6"
bright_blue = "#80b0ff"
bright_purple = "#b692ff"

[bjarneo]

Go through all of these one more time. Selection should probably not be part of the gradients.