Remove unused configurations and packages from laptop setup

- Removed USBGuard configuration and its associated comments from configuration.nix.
- Cleaned up flake.nix by removing unnecessary overlays.
- Updated home.nix to remove references to Helium and Proton, and added Steam.
- Deleted secrets.default.nix and secrets.secrets.yaml files for security reasons.
- Removed Omen laptop specific configuration from omen.nix.
- Deleted vencord.nix as it is no longer needed.

docs/GROUPS.md

@@ -17,10 +17,10 @@ For the Cybersecurity group, the home-manager module also sets up:
 
 ## Use in another flake
 
-Add this repo as an input:
+Add this repo as an input (update the URL to match your repository):
 
 ```nix
-inputs.nixy.url = "github:anotherhadi/nixy";
+inputs.nixy.url = "github:yourusername/nixy";
 ```
 
 Import the home-manager module in your home configuration:
@@ -30,15 +30,21 @@ Import the home-manager module in your home configuration:
   imports = [
     inputs.nixy.homeManagerModules.cybersecurity
     # inputs.nixy.homeManagerModules.dev
+    # inputs.nixy.homeManagerModules.basic-apps
+    # inputs.nixy.homeManagerModules.misc
   ];
 }
 ```
 
+See [GROUPS-REMOTE.md](GROUPS-REMOTE.md) for complete documentation on using groups with different remote URLs and troubleshooting tips.
+
 ## Quick shell without installing
 
 ```sh
-nix shell github:anotherhadi/nixy#cybersecurity
-nix shell github:anotherhadi/nixy#dev
+nix shell yourusername/nixy#cybersecurity
+nix shell yourusername/nixy#dev
 ```
 
 This drops you into a shell with all tools in `PATH`. No home-manager required, no wordlists or systemd units.
+
+Replace `yourusername/nixy` with your actual repository path.