chore: migrate omarchy state from ~/.config to ~/.local/state

Move all omarchy runtime state (themes, backgrounds, current theme)
from ~/.config/omarchy/current to ~/.local/state/omarchy/current
to keep the config dir free of generated files. Add mise task for
recreating symlinks and update credential helpers for tea.

script/omarchy-theme-remove

@@ -18,7 +18,7 @@ else
 fi
 
 THEMES_DIR="$HOME/.config/omarchy/themes"
-CURRENT_DIR="$HOME/.config/omarchy/current"
+CURRENT_DIR="$HOME/.local/state/omarchy/current"
 THEME_PATH="$THEMES_DIR/$THEME_NAME"
 
 # Ensure a theme was set