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/airootfs/etc/calamares/modules/users.conf

@@ -0,0 +1,40 @@
+---
+defaultGroups:
+  - name: users
+    must_exist: true
+    system: false
+  - name: lp
+    must_exist: false
+    system: true
+  - name: video
+    must_exist: false
+    system: true
+  - name: network
+    must_exist: false
+    system: true
+  - name: storage
+    must_exist: false
+    system: true
+  - name: wheel
+    must_exist: false
+    system: true
+  - name: audio
+    must_exist: false
+    system: true
+  - name: input
+    must_exist: false
+    system: true
+
+autologinGroup: autologin
+doAutologin: false
+sudoersGroup: wheel
+setRootPassword: false
+doReusePassword: true
+
+passwordRequirements:
+  minLength: 6
+  maxLength: -1
+  libpwquality:
+    - minlen=6
+
+allowWeakPasswords: false