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-resolve-airootfs

@@ -0,0 +1,29 @@
+#!/bin/bash
+# Resolve the real location of the live squashfs before Calamares' unpackfs
+# module runs, and leave a stable symlink for it to unpack from.
+#
+# archiso's own initcpio hook unmounts /run/archiso/bootmnt once copytoram has
+# copied the image to a tmpfs (/run/archiso/copytoram/airootfs.sfs) — and
+# copytoram=auto self-enables on most real hardware (non-optical boot device,
+# image under 4 GiB, enough free RAM), not just when explicitly requested. A
+# Calamares unpackfs.conf source path hardcoded to /run/archiso/bootmnt/...
+# would then point at nothing. Check both locations here, in a real script,
+# and hand unpackfs.conf one fixed path that always resolves.
+set -uo pipefail
+
+DEST="/run/archiso/resolved-airootfs.sfs"
+CANDIDATES=(
+    "/run/archiso/copytoram/airootfs.sfs"
+    "/run/archiso/bootmnt/arch/x86_64/airootfs.sfs"
+)
+
+for c in "${CANDIDATES[@]}"; do
+    if [ -f "$c" ]; then
+        ln -sf "$c" "$DEST"
+        echo "resolved live squashfs: $c -> $DEST"
+        exit 0
+    fi
+done
+
+echo "ERROR: could not find the live squashfs in any known location (checked: ${CANDIDATES[*]})" >&2
+exit 1