Fix install-breaking and live-boot bugs, verified on real hardware

Boot-critical (each confirmed with a real boot/install cycle, not just
code review):

- Live ISO's liveuser shell is zsh, but Hyprland autostart was written
  to .bash_profile (never runs) — moved to .zprofile, and switched to
  start-hyprland (Hyprland's own watchdog wrapper; raw `exec Hyprland`
  is no longer the recommended launch method).
- copytoram (self-enables on most real hardware: non-optical boot +
  image < 4GiB + enough free RAM) unmounts /run/archiso/bootmnt, which
  unpackfs.conf and bos-copy-kernel both hardcoded as their source —
  broke the installer outright on real hardware, confirmed by forcing
  copytoram=y. Added a resolver step for unpackfs, and switched the
  kernel copy to /usr/lib/modules/$(uname -r)/vmlinuz (part of the live
  squashfs itself, unaffected by copytoram).
- BIOS installs got no bootloader — post-install.sh only ever ran the
  UEFI grub-install path despite BOS shipping bios.syslinux. Added a
  BIOS branch with disk auto-detection.
- @snapshots/@log/@cache were never real: iso/partition.conf's
  btrfsSubvolumes key isn't part of this Calamares version's partition
  module schema at all (same class of bug as the userShell fix below —
  silently ignored). Calamares only natively creates @ and @home.
  post-install.sh now creates the three subvolumes by hand after
  unpackfs, migrates existing /var/log + /var/cache content into them
  before mounting over, and adds the fstab entries — verified end to
  end on real hardware, including grub-btrfs generating bootable
  snapshot menu entries. The unmount step in the existing snapper
  create-config dance also gained retry + lazy-unmount fallback after
  a real chroot run hit a transient busy-mount race.
- Default shell was bash instead of zsh post-install: users.conf's
  top-level `userShell` key isn't part of this Calamares version's
  users module schema either — the real key is nested (user.shell).
- graphical-session.target ships RefuseManualStart=yes (systemd
  convention), so the earlier attempt to activate it from hyprland.lua
  silently failed and breadclipd (WantedBy=graphical-session.target)
  never started. Starts breadclipd.service directly instead.
- /etc/os-release was never set (showed "Arch Linux"); live boot never
  had quiet/splash/plymouth wired in (raw kernel scroll the whole
  time) despite BOS already shipping a complete bread-logo+spinner
  plymouth theme for the installed system.

Also: generalized build-local.sh's per-service skel baking (previously
only breadd.service was hand-committed; breadbox-sync/breadmill/
breadclipd never shipped), added the four new bakery packages to
BREAD_BINS, removed the redundant cliphist/fzf clipboard pipeline in
favor of breadclip, mirrored fastfetch's bread-logo config into skel,
and fixed a stale bos-update comment.

iso/airootfs/usr/local/bin/bos-live-setup

@@ -34,15 +34,18 @@ fi
 
 # Start Hyprland on tty1 login; capture output and fall back to a shell so a
 # failed compositor start is visible rather than a blank looping cursor.
-cat >/home/liveuser/.bash_profile <<'EOF'
+# liveuser's shell is zsh (see useradd above), which never sources
+# .bash_profile — this must be .zprofile (zsh's login-shell hook) or it never
+# runs at all and the live session boots to a bare console.
+cat >/home/liveuser/.zprofile <<'EOF'
 if [[ "$(tty)" == /dev/tty1 ]] && [[ -z "$WAYLAND_DISPLAY" ]]; then
     export WLR_RENDERER_ALLOW_SOFTWARE=1
     export WLR_NO_HARDWARE_CURSORS=1
     # Log to a user-writable path (/var/log is root-only; redirecting there
     # would fail and silently keep the compositor from ever launching).
-    Hyprland &>/tmp/hyprland-live.log
+    start-hyprland &>/tmp/hyprland-live.log
     echo "Hyprland exited (rc=$?). Log: /tmp/hyprland-live.log"
-    exec bash -i
+    exec zsh -i
 fi
 EOF