Scaffold BOS repo: dotfiles, ISO profile, and bos-settings GTK4 app

Implements all four components from the BOS spec:
- dotfiles/: default Hyprland, bread, breadbox, breadcrumbs configs
- iso/: archiso profiledef, package list, Calamares YAML modules, post-install.sh
- bos-settings/: Cargo workspace with GTK4 settings app (8 views: snapshots,
  packages, bread, breadbar, breadbox, breadcrumbs, breadpad, hyprland)

https://claude.ai/code/session_01WszGHvCmxgcyTwNSkfLF9P

iso/profiledef.sh

@@ -0,0 +1,24 @@
+#!/usr/bin/env bash
+# shellcheck disable=SC2034
+
+iso_name="bos"
+iso_label="BOS_$(date +%Y%m)"
+iso_publisher="Breadway"
+iso_application="Bread Operating System"
+iso_version="$(date +%Y.%m.%d)"
+install_dir="arch"
+buildmodes=('iso')
+bootmodes=(
+    'bios.syslinux.mbr'
+    'bios.syslinux.eltorito'
+    'uefi-x64.systemd-boot.esp'
+    'uefi-x64.systemd-boot.eltorito'
+)
+arch="x86_64"
+pacman_conf="pacman.conf"
+airootfs_image_type="squashfs"
+airootfs_image_tool_options=('-comp' 'xz' '-Xbcj' 'x86' '-b' '1M' '-Xdict-size' '1M')
+file_permissions=(
+    ["/etc/shadow"]="0:0:400"
+    ["/etc/calamares/post-install.sh"]="0:0:755"
+)