theme: calm YoRHa lock screen and power menu; nvim and btop follow

The lock screen and the power menu lose the last Persona motion: no split
display type, no grid sweeping in behind a dark column, no tilted slabs, no
skewed password blocks or hard shake. Both are now one small group of type in
the dark — the porthole mark, a line of light display type, a status line, and
either a rounded password field that fills with dots or a NieR menu whose
selected row is a pill of light (rust for the session-ending three). The lock
keeps the wallpaper almost whole; a wrong password nudges the field once and
turns it to rust. P5Backdrop and the grid texture had no users left and go.

Neovim moves to a local yorha colorscheme (nvim submodule) and btop gets a
yorha theme with hairline boxes and grey-to-light gradients.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

btop/btop.conf

@@ -2,7 +2,7 @@
 
 #* Name of a btop++/bpytop/bashtop formatted ".theme" file, "Default" and "TTY" for builtin themes.
 #* Themes should be placed in "../share/btop/themes" relative to binary or "$HOME/.config/btop/themes"
-color_theme = "/home/narl/.config/btop/themes/catppuccin_mocha.theme"
+color_theme = "/home/narl/.config/btop/themes/yorha.theme"
 
 #* If the theme set background should be shown, set to False if you want terminal background transparency.
 theme_background = false