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)

packaging/tanin-calendar/PKGBUILD

@@ -0,0 +1,26 @@
+# Maintainer: Karim <karim@gabrielevarano.ch>
+#
+# tanin-calendar — TANINUX calendar app (GTK4 / libadwaita). A detailed agenda
+# over your calendars, read straight from Evolution Data Server (the same
+# backend GNOME Online Accounts feeds). Inherits the Fuji monochrome look from
+# tanin-libadwaita. German UI.
+pkgname=tanin-calendar
+pkgver=0.1.0
+pkgrel=1
+pkgdesc="TANINUX calendar — GTK4/libadwaita agenda over Evolution Data Server (GNOME Online Accounts)"
+arch=('any')
+url="https://taninux.kgva.ch"
+license=('GPL-3.0-or-later')
+depends=('python' 'python-gobject' 'gtk4' 'libadwaita'
+         'evolution-data-server' 'adwaita-icon-theme')
+optdepends=('gnome-online-accounts: add Google/Nextcloud/CalDAV calendars'
+            'tanin-libadwaita: Fuji monochrome theming for the app')
+
+package() {
+  install -Dm755 "$startdir/tanin-calendar" \
+    "$pkgdir/usr/bin/tanin-calendar"
+  install -Dm644 "$startdir/tanin-calendar.css" \
+    "$pkgdir/usr/share/tanin/calendar/tanin-calendar.css"
+  install -Dm644 "$startdir/ch.gabrielevarano.TaninCalendar.desktop" \
+    "$pkgdir/usr/share/applications/ch.gabrielevarano.TaninCalendar.desktop"
+}