Add Noctalia plugins config and disable defaults

Introduce `nooctalia-plugins` options to control nightly‑shell plugins
and make
their activation conditional.  Update host home‑modules to enable a
subset
of plugins (keybind‑cheatsheet, kde‑connect, screenshot, ntfy) on
desktop and
laptop configurations.  Disable numerous default applications and system
services (e.g., Zed, browsers, Docker, Flatpak, calendar, GameMode,
Steam,
media tools, communication apps) in the default host configuration.

hosts/default/system-modules.nix

@@ -2,14 +2,14 @@ _: {
   /*
   Container & Packaging
   */
-  docker.enable = true; # Docker: container runtime and management
+  docker.enable = false; # Docker: container runtime and management
   virtualbox.enable = false; # VirtualBox: PC emulator
   flatpak = {
-    enable = true; # Flatpak: universal packaging system for Linux
+    enable = false; # Flatpak: universal packaging system for Linux
     packages = {
       sober.enable = false; # Roblox client
-      warehouse.enable = true; # Flatpak manager
-      flatseal.enable = true; # Flatpak permissions manager
+      warehouse.enable = false; # Flatpak manager
+      flatseal.enable = false; # Flatpak permissions manager
       upscaler.enable = false; # Upscaler: Upscale and enhance images
     };
   };
@@ -22,14 +22,14 @@ _: {
   /*
   Calendar & Contacts
   */
-  calendar.enable = true; # GNOME Calendar: calendar and contacts application
+  calendar.enable = false; # GNOME Calendar: calendar and contacts application
 
   /*
   Gaming
   */
-  gamemode.enable = true; # GameMode: optimizes system performance for gaming
+  gamemode.enable = false; # GameMode: optimizes system performance for gaming
   gamescope.enable = false; # Gamescope: micro‑compositor for games
-  steam.enable = true; # Steam: platform for buying and playing games
+  steam.enable = false; # Steam: platform for buying and playing games
 
   /*
   Media & Graphics
@@ -59,26 +59,26 @@ _: {
     Gaming
     */
     prismlauncher.enable = false; # Prism Launcher: Minecraft modded launcher
-    spaceCadetPinball.enable = true; # SpaceCadet Pinball: classic pinball game
-    ttySolitaire.enable = true; # TTY Solitaire: terminal‑based solitaire game
+    spaceCadetPinball.enable = false; # SpaceCadet Pinball: classic pinball game
+    ttySolitaire.enable = false; # TTY Solitaire: terminal‑based solitaire game
     heroic.enable = false; # Native GOG, Epic, and Amazon Games Launcher for Linux, Windows and Mac
 
     /*
     Development Tools
     */
-    exercism.enable = true; # Exercism: coding practice platform
+    exercism.enable = false; # Exercism: coding practice platform
     lazygit.enable = false; # Lazygit: simple TUI for Git
-    jan.enable = true; # Jan: AI chat UI
+    jan.enable = false; # Jan: AI chat UI
     logisim-evolution.enable = false; # Logisim-Evolution: Digital logic designer and simulator
 
     /*
     Communication & Collaboration
     */
-    mattermost.enable = true; # Mattermost: open‑source Slack alternative
+    mattermost.enable = false; # Mattermost: open‑source Slack alternative
     slack.enable = false; # Slack: team communication and collaboration tool
-    tutanota.enable = true; # Tutanota: secure email client
-    signal.enable = true; # Signal: secure messaging app
-    teams.enable = true; # Teams-for-linux: Unofficial Microsoft Teams client for Linux
+    tutanota.enable = false; # Tutanota: secure email client
+    signal.enable = false; # Signal: secure messaging app
+    teams.enable = false; # Teams-for-linux: Unofficial Microsoft Teams client for Linux
     ferdium.enable = false; # Ferdium: All your services in one place built by the community
     notify.enable = false; # notify-client: Ntfy client application to receive everyday's notifications
     appImages.fluxer.enable = false; # Fluxer: Discord alternative
@@ -87,27 +87,27 @@ _: {
     Productivity / Knowledge Management
     */
     bitwarden.enable = false; # Bitwarden: password manager (desktop)
-    iotas.enable = true; # Iotas: lightweight notes manager
+    iotas.enable = false; # Iotas: lightweight notes manager
     logseq.enable = false; # Logseq: knowledge base and outliner
 
     /*
     Media & Graphics
     */
-    eyeOfGnome.enable = true; # Eye of GNOME: image viewer
+    eyeOfGnome.enable = false; # Eye of GNOME: image viewer
     switcheroo.enable = false; # Switcheroo: file conversion tool
     freetube.enable = false; # FreeTube: privacy‑friendly YouTube client
     gimp.enable = false; # GIMP: GNU Image Manipulation Program
     kdenlive.enable = false; # Kdenlive: video editing software
     pixieditor.enable = false; # Pixieditor: Universal editor for all your 2D needs
-    plex.enable = true; # Plex: media player and server client
-    jellyfin.enable = true; # Jellyfin: foss media player
+    plex.enable = false; # Plex: media player and server client
+    jellyfin.enable = false; # Jellyfin: foss media player
     appImages.losslesscut.enable = false; # Losslesscut: Swiss army knife of lossless video/audio editing
 
     /*
     Utilities / Misc
     */
-    eddieAirVPN.enable = true; # Eddie AirVPN: VPN client
-    gnomeCalculator.enable = true; # gnomeCalculator: simple calculator
+    eddieAirVPN.enable = false; # Eddie AirVPN: VPN client
+    gnomeCalculator.enable = false; # gnomeCalculator: simple calculator
     gedit.enable = false; # Gedit: GNOME text editor
     winboat.enable = false; # Winboat: Windows remote desktop via RDP
     adb.enable = false; # ADB: Android SDK platform tools