v0.4.0: branding refresh, breadpaper baked in, bos-settings 0.4.0

- Move assets to assets/ directory (bread_white.svg, icons 256/512/1024px)
- Update Calamares branding + Plymouth theme logos
- Bake breadpaper (wallpaper manager + pywal) into /etc/skel alongside the
  rest of the bread ecosystem — previously missing from the ISO build
- Bump bos-settings to 0.4.0

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FHr5CeufsAfTrt41XoApir

build-local.sh

@@ -44,7 +44,7 @@ grep airootfs_image_tool_options "$STAGE/profiledef.sh"
 # created from skel (the live user and the installed user) then gets the same
 # versions `bakery list` reports here, fully offline. Copied at build time so the
 # binaries never bloat the git repo and always track the current bakery state.
-BREAD_BINS=(bakery bread breadd breadman breadbar breadbox breadbox-sync breadcrumbs breadpad bread-theme)
+BREAD_BINS=(bakery bread breadd breadman breadbar breadbox breadbox-sync breadcrumbs breadpad breadpaper bread-theme)
 LAPTOP_HOME="${LAPTOP_HOME:-$(getent passwd "${SUDO_USER:-$USER}" | cut -d: -f6)}"
 BAKERY_BIN="$LAPTOP_HOME/.local/bin"
 BAKERY_STATE="$LAPTOP_HOME/.local/state/bakery"