feat(deploy): BetterFrame plymouth boot splash

Replace Pi rainbow + kernel boot text with a black BG + centered BF logo
during boot. Installer renders logo.png from the existing SVG asset via
rsvg-convert, drops a script-based plymouth theme, and appends the
quiet/splash flags to cmdline.txt + disable_splash=1 in config.txt.

cmdline.txt edits are idempotent: each flag only added if missing.

deploy/plymouth/betterframe/betterframe.plymouth

@@ -0,0 +1,8 @@
+[Plymouth Theme]
+Name=BetterFrame
+Description=BetterFrame boot splash
+ModuleName=script
+
+[script]
+ImageDir=/usr/share/plymouth/themes/betterframe
+ScriptFile=/usr/share/plymouth/themes/betterframe/betterframe.script

deploy/plymouth/betterframe/betterframe.script

@@ -0,0 +1,18 @@
+// BetterFrame plymouth splash: solid black background, centered logo.
+// Logo is generated from server/src/web-static/betterframe-logo.svg at
+// install time by setup-pi-kiosk.sh (rsvg-convert → logo.png).
+
+Window.SetBackgroundTopColor(0.0, 0.0, 0.0);
+Window.SetBackgroundBottomColor(0.0, 0.0, 0.0);
+
+logo.image = Image("logo.png");
+logo.sprite = Sprite(logo.image);
+logo.sprite.SetX(Window.GetWidth() / 2 - logo.image.GetWidth() / 2);
+logo.sprite.SetY(Window.GetHeight() / 2 - logo.image.GetHeight() / 2);
+
+// Hide all message and progress reporting — keep the splash clean.
+fun message_callback (text) { }
+fun update_status_callback (status) { }
+fun display_password_callback (prompt, bullets) { }
+fun display_question_callback (prompt, entry) { }
+fun display_normal_callback () { }

deploy/scripts/setup-pi-kiosk.sh

@@ -111,7 +111,8 @@ if [ "${INSTALL_KIOSK}" = "1" ]; then
     libwebkitgtk-6.0-dev pkg-config build-essential \
     gstreamer1.0-plugins-base gstreamer1.0-plugins-good \
     gstreamer1.0-plugins-bad gstreamer1.0-libav \
-    v4l-utils wlr-randr
+    v4l-utils wlr-randr \
+    plymouth plymouth-themes librsvg2-bin
 
   systemctl enable --now seatd
 fi
@@ -192,6 +193,43 @@ EOF
   systemctl enable betterframe-kiosk.service
   # Restart picks up new binary on re-run.
   systemctl restart betterframe-kiosk.service || true
+
+  # --------------------------------------------------------------------------
+  # 9. Plymouth boot splash — hide kernel text + Pi rainbow, show BF logo
+  # --------------------------------------------------------------------------
+  echo "==> Installing BetterFrame plymouth theme"
+  THEME_DIR="/usr/share/plymouth/themes/betterframe"
+  install -d -m 755 "${THEME_DIR}"
+  install -m 644 "${REPO_ROOT}/deploy/plymouth/betterframe/betterframe.plymouth" "${THEME_DIR}/"
+  install -m 644 "${REPO_ROOT}/deploy/plymouth/betterframe/betterframe.script"   "${THEME_DIR}/"
+  rsvg-convert -w 480 "${REPO_ROOT}/server/src/web-static/betterframe-logo.svg" \
+    -o "${THEME_DIR}/logo.png"
+  plymouth-set-default-theme -R betterframe
+
+  # Find the boot config / cmdline file. Bookworm uses /boot/firmware/, older
+  # Pi images use /boot/.
+  if [ -f /boot/firmware/cmdline.txt ]; then
+    BOOT_DIR=/boot/firmware
+  else
+    BOOT_DIR=/boot
+  fi
+  CMDLINE="${BOOT_DIR}/cmdline.txt"
+  CONFIG="${BOOT_DIR}/config.txt"
+
+  if [ -f "${CMDLINE}" ]; then
+    # cmdline.txt is a single line. Append missing flags only.
+    for flag in quiet splash plymouth.ignore-serial-consoles "loglevel=0" "vt.global_cursor_default=0" logo.nologo; do
+      if ! grep -qw -- "${flag}" "${CMDLINE}"; then
+        sed -i "s|\$| ${flag}|" "${CMDLINE}"
+      fi
+    done
+  fi
+  if [ -f "${CONFIG}" ]; then
+    # Pi firmware rainbow splash off.
+    if ! grep -q "^disable_splash=1" "${CONFIG}"; then
+      printf '\n# BetterFrame: disable firmware rainbow splash\ndisable_splash=1\n' >> "${CONFIG}"
+    fi
+  fi
 fi
 
 echo "==> Done."