Make BOS a complete, bootable, themed desktop OS

Install/boot reliability:
- Use native Calamares initcpiocfg/initcpio + explicit grub-install (nvram +
  --removable) in post-install; drop the flaky native bootloader/grubcfg modules.
- mount.conf: bind /proc /sys /dev (devtmpfs) /run + efivars into the chroot.
- bos-copy-kernel: stage kernel + write a stock mkinitcpio preset (replace the
  archiso preset). Per-service systemctl enable (fixes NetworkManager et al.
  silently not enabling due to the all-or-nothing grub-btrfs.path name).

System completeness:
- greetd + tuigreet graphical login; installed pacman.conf + working mirrorlist;
  base CLI tools (nano, micro, vim, htop, …); amd/intel-ucode; tlp + hypridle
  power management; systemd-timesyncd, fstrim.timer; wpa_supplicant wifi; Zen
  browser (republished to the [Breadway] repo).

Desktop + theming:
- Native Lua Hyprland config (hyprland.lua) with curated standard binds; kitty
  (blur) replaces foot; awww wallpaper + pywal palette (tamed to a black base
  with warm accents); GTK dark mode.
- Plymouth boot splash (bos theme: logo + spinner + status) via plymouthcfg.
- Varela Round font; Calamares bread-palette sidebar (logo/black-region polish
  still pending).

iso/airootfs/etc/calamares/branding/bos/branding.desc

@@ -23,7 +23,7 @@ slideshow:               "show.qml"
 slideshowAPI:            2
 
 style:
-    sidebarBackground:   "#3b4252"
-    sidebarText:         "#eceff4"
-    sidebarTextSelect:   "#5e81ac"
-    sidebarTextHighlight: "#eceff4"
+    sidebarBackground:    "#230b00"
+    sidebarText:          "#f1dcbd"
+    sidebarTextSelect:    "#EAB672"
+    sidebarTextHighlight: "#ffffff"

iso/airootfs/etc/calamares/branding/bos/stylesheet.qss

@@ -0,0 +1,23 @@
+/* BOS Calamares styling.
+ *
+ * The branding `style:` sidebar keys were being overridden, leaving the
+ * step tabs invisible. This forces them: bread-palette sidebar with clearly
+ * legible step labels. (A full installer retheme is tracked separately.)
+ */
+
+/* Left sidebar / progress steps */
+#sidebarApp {
+    background-color: #230b00;
+}
+
+#sidebarApp QLabel {
+    color: #f1dcbd;
+    font-size: 11pt;
+    padding: 3px 0;
+}
+
+/* Logo at the top of the sidebar — keep aspect ratio, don't stretch */
+#logoApp {
+    qproperty-alignment: AlignCenter;
+    margin: 14px 8px;
+}