Cadence weekly (format oreo) + paquets/Flatpak communs sur toutes les machines

- system.autoUpgrade.dates : daily -> weekly, même cadence que oreo
- hosts/common/desktop.nix : ajoute la liste de paquets demandée (System
  tools, Office, Communication/Media) + Flatpak (repo/install/update) +
  AppImage, déjà présents sur oreo, maintenant sur usagers aussi

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

hosts/common/desktop.nix

@@ -78,8 +78,84 @@
   };
 
   environment.systemPackages = with pkgs; [
+    # === Office/Notes ===
     libreoffice
+    pdfarranger
+    simple-scan
+
+    # === System tools ===
+    btop
+    unzip
+    screenfetch
+    tmux
+    fwupd
+    fwupd-efi
+    ncdu
+    gdu
+    hplip
+    gutenprint
+    cups
+    inxi
+    ntfs3g
+
+    # === Communication/Media ===
     thunderbird
+    ffmpeg
     vlc
+    mpv
+    strawberry
   ];
+
+  # Flatpak
+  services.flatpak.enable = true;
+  xdg.portal.enable = true;
+  xdg.portal.extraPortals = [ pkgs.xdg-desktop-portal-gtk ];
+
+  systemd.services.flatpak-repo = {
+    wantedBy = [ "multi-user.target" ];
+    after = [ "network-online.target" ];
+    wants = [ "network-online.target" ];
+    serviceConfig = {
+      Type = "oneshot";
+      RemainAfterExit = true;
+    };
+    path = [ pkgs.flatpak ];
+    script = ''
+      flatpak remote-add --if-not-exists flathub \
+        https://dl.flathub.org/repo/flathub.flatpakrepo
+    '';
+  };
+
+  systemd.services.flatpak-install = {
+    wantedBy = [ "multi-user.target" ];
+    after = [
+      "flatpak-repo.service"
+      "network-online.target"
+    ];
+    wants = [ "network-online.target" ];
+    requires = [ "flatpak-repo.service" ];
+    serviceConfig = {
+      Type = "oneshot";
+      RemainAfterExit = true;
+    };
+    path = [ pkgs.flatpak ];
+    script = ''
+      flatpak install -y flathub \
+      net.waterfox.waterfox \
+       eu.betterbird.Betterbird
+    '';
+  };
+
+  systemd.services.flatpak-update = {
+    wantedBy = [ "multi-user.target" ];
+    path = [ pkgs.flatpak ];
+    script = ''
+      flatpak update -y
+    '';
+  };
+
+  programs.appimage = {
+    enable = true;
+    binfmt = true;
+  };
 }