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)

distro/MANIFEST.md

@@ -19,7 +19,7 @@ Dark, monochrome, libadwaita, rounded, soft short shadows.
 | bg / fg    | `#0f0f0f` / `#f0f0f0`| theme                          |
 | UI font    | Inter (Medium)       | apps, bar                      |
 | icon font  | Iosevka Nerd Font    | `nf-md-*` glyphs               |
-| icon theme | Papirus              | dock app icons                 |
+| icon theme | Adwaita + `tanin-icons` | base + Fuji-accent folders (`Tanin-<accent>`) |
 
 ## The stack (what it boots into)
 
@@ -30,7 +30,7 @@ Dark, monochrome, libadwaita, rounded, soft short shadows.
 | Bar/dock/panels  | **eww** + Spotlight                 | `eww`, `tanin-eww`               |
 | Notifications    | **tiramisu** (headless) + eww UI    | `tiramisu`                       |
 | Terminal         | foot                                | `foot`                           |
-| Wallpaper        | waypaper                            | `waypaper`                       |
+| Wallpaper        | waypaper (swaybg) + blurred Overview backdrop (awww) | `waypaper`, `awww`, `imagemagick` |
 | Apps             | tsettings · thub · taninux (TUI)    | `taninux`                        |
 | GTK4 theme       | **Fuji** recolour, light + dark     | `tanin-libadwaita`               |
 | Portals          | gtk (dark mode) + gnome (screencast)| `xdg-desktop-portal-{gtk,gnome}` |
@@ -54,6 +54,7 @@ AUR                                        →  OPT-IN only (paru = optdepend)
 | `taninux`       | tsettings + thub + TUI, helper, polkit, .desktop  | ready             |
 | `tanin-greet`   | custom GTK4 greeter for greetd → `/etc/greetd/`   | ready (preview)   |
 | `tanin-libadwaita` | Fuji libadwaita recolour, light + dark (pills) | ready (preview)   |
+| `tanin-icons`   | Adwaita overlay, folders recoloured per accent (`Tanin-<accent>`) | ready |
 | `tanin-eww`     | eww bar/dock/panels + niri config → `/usr/share/tanin/skel/.config` | ready |
 | `tanin-setup`   | seed `~/.config` + enable session target          | ready             |
 | `tanin-desktop` | metapackage pulling the whole environment (niri)  | ready |
@@ -86,6 +87,16 @@ waypaper/cliphist) are exactly why `[tanin]` must carry rebuilt AUR packages.
 4. **ISO** — ✅ scaffolded in `iso/` (archiso releng-base + overrides). Calamares `packages`
    module installs `tanin-desktop`; greetd + tanin-greet enabled; session target wired.
 
+### Overview backdrop (blurred wallpaper)
+niri's Overview shows a flat grey backdrop behind the zoomed-out workspaces. We
+fill it with a blurred copy of the wallpaper via a **second** background surface:
+`awww` (namespace `awww-daemon`) shows the blurred image, and a niri
+`layer-rule … place-within-backdrop true` moves it into the backdrop (so the
+sharp swaybg wallpaper stays on the desktop). niri has no blur of its own — the
+copy is pre-blurred by `~/.config/eww/scripts/overview-backdrop.sh` with
+ImageMagick. Started via niri `spawn-at-startup "… overview-backdrop.sh start"`
+and regenerated on each wallpaper change via waypaper's `post_command`.
+
 ### Session / dark-mode fix
 libadwaita apps read light/dark via `org.freedesktop.portal.Settings`, which
 needs `graphical-session.target` active. `tanin-setup` installs