feat(branding): restore the boot splash, SDDM theme, and greeter background

Neither the Plymouth theme nor the login/lock theming was ever installed by a
restore, so a rebuilt box came up with stock distro branding.

bin/boot-branding.sh installs all three, and the desktop stage of
restore-linux.sh calls it. Each block self-skips when its greeter is absent or
already current, so it is cheap to re-run and works whether the box boots
lightdm or SDDM:

- Plymouth: a real copy under /usr/share/plymouth/themes, not a symlink into
  the user home. The stock initramfs hook copies the theme path verbatim, so a
  symlink into an unmounted home dangles at early boot and Plymouth drops to
  text mode -- which is what assets/boot/initramfs-hook-my-custom-logo existed
  to work around. With a real copy that hook is unnecessary.
- SDDM: the NexusOS-QML theme, selected via /etc/sddm.conf.d.
- slick-greeter: cannot lay out a custom login screen, so the logo and wordmark
  are baked into assets/themes/greeter/greeter-background.svg and its own
  centered login box lands underneath.

Main.qml now loads background.png instead of background.svg. QtSvg implements
SVG Tiny 1.2, which has no <pattern>, so the brushed-metal and machine-line
textures silently dropped out at runtime. librsvg renders them, so the SVG is
rasterized at 1920x1200 and committed alongside it; the regeneration command is
in the comment above the source: line.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

assets/themes/KDE/sddm/NexusOS-QML/Main.qml

@@ -31,7 +31,16 @@ Rectangle {
 
     Image {
         anchors.fill: parent
-        source: "assets/background.svg"
+        // background.png, not the .svg it was rendered from: QtSvg implements
+        // SVG Tiny 1.2, which has no <pattern>, so the brushed-metal and
+        // machine-line textures silently drop out ("Could not resolve property:
+        // #brushLines"). librsvg renders them fine, so the SVG is rasterized at
+        // 1920x1200 and committed. Regenerate after editing background.svg:
+        //   python3 -c 'import gi; gi.require_version("GdkPixbuf","2.0"); \
+        //     from gi.repository import GdkPixbuf as G; \
+        //     G.Pixbuf.new_from_file_at_scale("assets/background.svg",1920,1200,False) \
+        //      .savev("assets/background.png","png",["compression"],["9"])'
+        source: "assets/background.png"
         fillMode: Image.PreserveAspectCrop
         smooth: true
         asynchronous: false
@@ -71,7 +80,7 @@ Rectangle {
 
     Text {
         id: brandLabel
-        text: "NexusOS"
+        text: "Welcome to NexusOS"
         color: textPrimary
         font.family: "Sans"
         font.pixelSize: 28

bin/boot-branding.sh

@@ -0,0 +1,118 @@
+#!/bin/bash
+# NexusOS boot-time branding: the Plymouth boot splash and the LightDM greeter
+# (which is also what you see on lock -- light-locker just switches to it).
+#
+# Both are system-level and need root, which is why this is a standalone script
+# rather than part of assets/themes/install-theme.sh.
+#
+# Usage: sudo bin/boot-branding.sh [--uninstall]
+set -euo pipefail
+
+NEXUS_ROOT="${NEXUS_ROOT:-$(cd "$(dirname "$(realpath "$0")")/.." && pwd)}"
+
+# Plymouth. A real copy is placed under /usr/share/plymouth/themes -- NOT a
+# symlink into /home. The stock initramfs plymouth hook copies the theme path
+# verbatim, so a symlink into an unmounted /home dangles at early boot and
+# Plymouth falls back to text mode. That is what
+# assets/boot/initramfs-hook-my-custom-logo exists to work around; with a real
+# copy the hook is unnecessary.
+SRC="$NEXUS_ROOT/assets/boot/my-custom-logo"
+DEST=/usr/share/plymouth/themes/my-custom-logo
+THEME="$DEST/my-custom-logo.plymouth"
+
+# Greeter. slick-greeter cannot lay out a custom login screen the way the
+# NexusOS-QML SDDM theme does, so the logo and wordmark are baked into the
+# background image instead and the greeter's own centered login box lands under
+# them. The SVG is used as-is: gdk-pixbuf's SVG loader is installed, so there is
+# nothing to rasterize. Copied out of the repo because the greeter runs as user
+# `lightdm` and the user home is 0750, so nothing in here is readable to it.
+GREETER_ART="$NEXUS_ROOT/assets/themes/greeter/greeter-background.svg"
+GREETER_DIR=/usr/share/nexusos
+GREETER_CONF=/etc/lightdm/slick-greeter.conf
+
+# SDDM. Its greeter is a QML app, so unlike slick-greeter it can draw the real
+# layout (logo, wordmark, login box, clock) -- this is the theme the design was
+# written for. Installed whenever sddm is present, regardless of which display
+# manager is currently active, so switching between the two needs no re-run.
+SDDM_SRC="$NEXUS_ROOT/assets/themes/KDE/sddm/NexusOS-QML"
+SDDM_DEST=/usr/share/sddm/themes/NexusOS-QML
+SDDM_CONF=/etc/sddm.conf.d/nexusos.conf
+
+[ "$(id -u)" -eq 0 ] || { echo "run with sudo"; exit 1; }
+
+if [ "${1:-}" = "--uninstall" ]; then
+	update-alternatives --remove default.plymouth "$THEME" 2>/dev/null || true
+	rm -rf "$DEST" "$GREETER_DIR" "$GREETER_CONF" "$SDDM_DEST" "$SDDM_CONF"
+	command -v update-initramfs >/dev/null && update-initramfs -u
+	echo "reverted to the distro defaults"
+	exit 0
+fi
+
+# --- Plymouth boot splash -----------------------------------------------------
+if [ ! -d "$SRC" ]; then
+	echo "missing theme source: $SRC -- skipping boot splash"
+elif ! command -v update-initramfs >/dev/null || [ ! -d /usr/share/plymouth/themes ]; then
+	echo "no Plymouth on this box -- skipping boot splash"
+# update-initramfs is slow, and a restore runs this every time. Bail out when the
+# installed copy already matches the repo and the alternative already points here.
+elif diff -rq "$SRC" "$DEST" >/dev/null 2>&1 &&
+     [ "$(readlink -f /usr/share/plymouth/themes/default.plymouth)" = "$THEME" ]; then
+	echo "boot splash already installed"
+else
+	rm -rf "$DEST"
+	cp -aL "$SRC" "$DEST"
+	chown -R root:root "$DEST"
+	chmod -R a+rX,go-w "$DEST"
+
+	update-alternatives --install /usr/share/plymouth/themes/default.plymouth \
+		default.plymouth "$THEME" 300
+	update-alternatives --set default.plymouth "$THEME"
+	update-initramfs -u
+	echo "boot splash installed"
+fi
+
+# --- LightDM greeter (login + lock) -------------------------------------------
+# Only slick-greeter is configured here; it's what Mint/XFCE ships and it reads
+# this file directly. theme-name is deliberately left alone -- the NexusOS GTK
+# theme lives in ~/.themes, which the lightdm user cannot read, so pointing at it
+# would just fall back silently. Colors below are the NexusOS-QML palette
+# (theme.conf: bgDark).
+if [ ! -f "$GREETER_ART" ]; then
+	echo "missing $GREETER_ART -- skipping greeter"
+elif ! command -v slick-greeter >/dev/null; then
+	echo "no slick-greeter on this box -- skipping greeter"
+else
+	install -D -m 644 -o root -g root "$GREETER_ART" "$GREETER_DIR/greeter-background.svg"
+	cat > "$GREETER_CONF" <<EOF
+[Greeter]
+background=$GREETER_DIR/greeter-background.svg
+background-color=#0a0e1a
+draw-user-backgrounds=false
+draw-grid=false
+content-align=center
+stretch-background-across-monitors=false
+EOF
+	chmod 644 "$GREETER_CONF"
+	echo "greeter background installed"
+fi
+
+# --- SDDM greeter -------------------------------------------------------------
+if [ ! -d "$SDDM_SRC" ]; then
+	echo "missing $SDDM_SRC -- skipping SDDM theme"
+elif [ ! -d /usr/share/sddm/themes ]; then
+	echo "no SDDM on this box -- skipping SDDM theme"
+else
+	rm -rf "$SDDM_DEST"
+	cp -aL "$SDDM_SRC" "$SDDM_DEST"
+	chown -R root:root "$SDDM_DEST"
+	chmod -R a+rX,go-w "$SDDM_DEST"
+	install -d -m 755 /etc/sddm.conf.d
+	cat > "$SDDM_CONF" <<EOF
+[Theme]
+Current=NexusOS-QML
+EOF
+	chmod 644 "$SDDM_CONF"
+	echo "SDDM theme installed"
+fi
+
+echo "done -- reboot to see it."

bin/restore-linux.sh

@@ -196,6 +196,15 @@ else
     echo "Warning: $panel_installer not found — skipping panel install."
 fi
 
+# Boot branding — the Plymouth splash. Not XFCE-specific, but it's cosmetic and
+# writes outside the repo, so it belongs to the skippable stage like os-release
+# below. Self-skips when the theme is already installed (initramfs rebuild is slow).
+if [ -x "$NEXUS_ROOT/bin/boot-branding.sh" ]; then
+    echo ""
+    echo "Installing NexusOS boot branding (splash + greeter)..."
+    sudo "$NEXUS_ROOT/bin/boot-branding.sh" || echo "Warning: boot branding skipped."
+fi
+
 # Distro branding — the About dialog / neofetch read /etc/os-release.
 if grep -q '^ID=linuxmint' /etc/os-release 2>/dev/null && ! grep -q 'NexusOS' /etc/os-release; then
     echo ""