gui: native libadwaita-free UI backend + dark shell; packaging/iso updates

- gui/ui: native GTK4 widget vocabulary (.tn-*) behind the ui.* seam,
  default backend now native; style_apple.css design language
- shell: sidebar/topbar/content all #0f0f0f in dark (matches eww panels)
- new pages: wine, online_accounts
- packaging: tanin-icons (accent folder theme), tanin-calendar, gtklock,
  taninux-gtk3-theme, flatpak install handler
- iso/distro: profile + manifest tweaks (ISO binary not included)

iso/build-profile/airootfs/etc/calamares/modules/shellprocess-striplive.conf

@@ -1,12 +1,13 @@
 ---
 dontChroot: false
 timeout: 30
-# Remove the live-only installer bits from the installed target so it boots the
-# desktop (greetd) instead of auto-launching Calamares.
+# Turn the cloned live image into a normal installed system:
+#  - drop the live installer launcher
+#  - restore the greetd config to the tanin-greet greeter (the live used an
+#    initial_session that auto-ran Calamares)
+#  - boot to the desktop; seatd is live-only (greetd uses logind on the target)
 script:
-- "rm -f /etc/systemd/system/getty@tty1.service.d/autologin.conf"
-- "rmdir --ignore-fail-on-non-empty /etc/systemd/system/getty@tty1.service.d 2>/dev/null || true"
-- "rm -f /root/.zprofile"
 - "rm -f /usr/local/bin/tanin-installer"
+- "install -Dm644 /usr/share/tanin/greetd/config.toml /etc/greetd/config.toml"
 - "systemctl set-default graphical.target"
 - "systemctl disable seatd.service"

iso/build-profile/airootfs/etc/systemd/system/getty@tty1.service.d/autologin.conf

@@ -1,3 +1,3 @@
 [Service]
 ExecStart=
-ExecStart=-/usr/bin/agetty --autologin root --noclear %I 38400 linux
+ExecStart=-/usr/bin/agetty --noreset --noclear --autologin root - ${TERM}