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/partition.conf

@@ -0,0 +1,29 @@
+---
+efiSystemPartition: "/boot/efi"
+efiSystemPartitionSize: "512M"
+efiSystemPartitionName: "EFI"
+
+defaultFileSystemType: "btrfs"
+
+btrfsSubvolumes:
+  - mountPoint: /
+    subvolume: "@"
+    mountOptions: "noatime,compress=zstd,space_cache=v2"
+  - mountPoint: /home
+    subvolume: "@home"
+    mountOptions: "noatime,compress=zstd,space_cache=v2"
+  - mountPoint: /.snapshots
+    subvolume: "@snapshots"
+    mountOptions: "noatime,compress=zstd,space_cache=v2"
+  - mountPoint: /var/log
+    subvolume: "@log"
+    mountOptions: "noatime,compress=zstd,space_cache=v2"
+  - mountPoint: /var/cache
+    subvolume: "@cache"
+    mountOptions: "noatime,compress=zstd,space_cache=v2"
+
+userSwapChoices:
+  - none
+  - small
+  - suspend
+  - file