Phase 1/2 complete: system tray (XEMBED) + Plymouth boot splash

System tray in skydeskbar (Phase 1 #4):
- Claims _NET_SYSTEM_TRAY_S<screen> selection on startup and
  broadcasts MANAGER so nm-applet and other tray clients connect
- Handles _NET_SYSTEM_TRAY_OPCODE dock requests: XReparentWindow
  icon into the deskbar, sends XEMBED_EMBEDDED_NOTIFY
- Tray section is zero-height when empty; expands to DB_TRAY_H=26px
  when first icon embeds, shrinking back when last icon exits
- DestroyNotify / ReparentNotify clean up the icon list and
  reposition remaining icons; SelectionClear hands off gracefully
- Icon positions are updated (db_tray_reposition) whenever the app
  list changes and shifts the tray section vertically

Plymouth boot splash (Phase 2 #10):
- 'skyos' script-module theme: dark navy (#111520) background,
  "SkyOS" logo in accent blue (#90BBEE), thin progress bar
- 1×1 pixel bar_bg.png / bar_fg.png scaled at runtime by the
  Plymouth script — no large PNGs committed to the repo
- logo.png generated at build time by ImageMagick (same tool used
  for the wallpaper); build continues if ImageMagick is absent
- mkinitcpio HOOKS: added 'plymouth' after 'udev'
- Kernel cmdline: added 'splash' for UEFI systemd-boot entry
- customize_airootfs.sh: plymouth-set-default-theme skyos

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

iso/docker/entrypoint.sh

@@ -101,6 +101,7 @@ git
 sudo
 bash-completion
 fastfetch
+plymouth
 PKGS
 
 # ── 3. airootfs overlay — files that land in the live system ─────────
@@ -188,7 +189,7 @@ cat > "$AIROOTFS/etc/mkinitcpio.conf.d/archiso.conf" <<'MKCONF'
 MODULES=()
 BINARIES=()
 FILES=()
-HOOKS=(base udev microcode archiso block filesystems keyboard)
+HOOKS=(base udev plymouth microcode archiso block filesystems keyboard)
 MKCONF
 echo ">>> Live initramfs HOOKS: base udev microcode archiso block filesystems keyboard"
 
@@ -531,6 +532,83 @@ gtk-icon-theme-name=Adwaita
 gtk-cursor-theme-name=DMZ-White
 GTK3
 
+# ── Plymouth dark navy boot splash ───────────────────────────────────
+echo ">>> Creating Plymouth theme..."
+PLYM="$AIROOTFS/usr/share/plymouth/themes/skyos"
+mkdir -p "$PLYM"
+
+cat > "$PLYM/skyos.plymouth" <<'PLYMDEF'
+[Plymouth Theme]
+Name=SkyOS
+Description=SkyOS dark navy boot splash
+ModuleName=script
+
+[script]
+ImageDir=/usr/share/plymouth/themes/skyos
+ScriptFile=/usr/share/plymouth/themes/skyos/skyos.script
+PLYMDEF
+
+cat > "$PLYM/skyos.script" <<'PLYMSCRIPT'
+# SkyOS Plymouth boot splash — dark navy + accent blue progress bar
+
+W = Window.GetWidth();
+H = Window.GetHeight();
+
+# Solid dark navy background
+Window.SetBackgroundTopColor(0.067, 0.082, 0.125);
+Window.SetBackgroundBottomColor(0.040, 0.055, 0.090);
+
+# Logo (centered, upper third of screen)
+logo = Image("logo.png");
+logo_sprite = Sprite(logo);
+logo_sprite.SetPosition(
+    Math.Int((W - logo.GetWidth())  / 2),
+    Math.Int(H * 0.40 - logo.GetHeight() / 2),
+    1
+);
+
+# Progress bar
+BAR_W = Math.Int(Math.Min(W * 0.42, 440));
+BAR_H = 4;
+bar_x = Math.Int((W - BAR_W) / 2);
+bar_y = Math.Int(H * 0.72);
+
+# Bar background track (dark blue-grey)
+bar_bg = Image("bar_bg.png").Scale(BAR_W, BAR_H);
+bar_bg_sprite = Sprite(bar_bg);
+bar_bg_sprite.SetPosition(bar_x, bar_y, 2);
+
+# Bar fill (accent blue, grows with progress)
+bar_fill_sprite = Sprite();
+bar_fill_sprite.SetPosition(bar_x, bar_y, 3);
+
+fun boot_progress_callback(time, progress) {
+    fill_w = Math.Int(BAR_W * progress);
+    if (fill_w < 2) fill_w = 2;
+    bar_fill = Image("bar_fg.png").Scale(fill_w, BAR_H);
+    bar_fill_sprite.SetImage(bar_fill);
+}
+
+Plymouth.SetBootProgressFunction(boot_progress_callback);
+PLYMSCRIPT
+
+# Generate PNG assets (ImageMagick is used above for the wallpaper)
+if command -v convert &>/dev/null; then
+    # Logo: "SkyOS" in accent blue on transparent background
+    convert -size 340x90 xc:none \
+        -font DejaVu-Sans-Bold -pointsize 62 \
+        -fill "#90BBEE" -gravity center \
+        -annotate 0 "SkyOS" \
+        "$PLYM/logo.png" 2>/dev/null \
+        && echo "    Plymouth logo generated." \
+        || echo "    Plymouth logo generation failed (non-fatal)."
+    # 1×1 pixel images — scaled at runtime by the script
+    convert -size 1x1 xc:"#1C2840" "$PLYM/bar_bg.png" 2>/dev/null || true
+    convert -size 1x1 xc:"#1E58A8" "$PLYM/bar_fg.png" 2>/dev/null || true
+else
+    echo "    ImageMagick not available — Plymouth PNGs skipped."
+fi
+
 # ── Mac hardware: libinput touchpad config ────────────────────────────
 mkdir -p "$AIROOTFS/etc/X11/xorg.conf.d"
 cat > "$AIROOTFS/etc/X11/xorg.conf.d/40-libinput.conf" <<'TOUCHPAD'
@@ -626,7 +704,7 @@ cat > "$PROFILE/efiboot/loader/entries/skyos.conf" <<'ENTRY'
 title   SkyOS
 linux   /arch/boot/x86_64/vmlinuz-linux
 initrd  /arch/boot/x86_64/initramfs-linux.img
-options archisobasedir=arch archisolabel=%ARCHISO_LABEL% quiet loglevel=3
+options archisobasedir=arch archisolabel=%ARCHISO_LABEL% quiet splash loglevel=3
 ENTRY
 
 
@@ -694,6 +772,9 @@ update-desktop-database 2>/dev/null || true
 # Fontconfig cache
 fc-cache -f 2>/dev/null || true
 
+# Plymouth: set SkyOS as the default theme (archiso runs mkinitcpio after this)
+plymouth-set-default-theme skyos 2>/dev/null || true
+
 # xscreensaver config (screen lock)
 mkdir -p /etc/skel
 cat > /etc/skel/.xscreensaver <<'SS'