feat(upstream): switch to remote git repository for engine

- Update installer to use git+https://git.bemagri.xyz/bernardo/Nomarchy.git
- Remove redundant bundling/copying of the engine to /etc/nixos/nomarchy
- Expose all themes via xdg.dataFile for script accessibility
- Update theme scripts to resolve directories via local share instead of hardcoded system paths
- Update documentation to reflect the new remote-first architecture

installer/install-nomarchy.sh

@@ -269,7 +269,7 @@ cat <<EOF > /mnt/etc/nixos/flake.nix
 
   inputs = {
     nixpkgs.url = "github:nixos/nixpkgs/nixos-25.11";
-    nomarchy.url = "path:./nomarchy"; # Offline bundled nomarchy
+    nomarchy.url = "git+https://git.bemagri.xyz/bernardo/Nomarchy.git";
     
     nixos-hardware.url = "github:NixOS/nixos-hardware/master";
     home-manager = {
@@ -318,11 +318,6 @@ cat <<EOF > /mnt/etc/nixos/flake.nix
 }
 EOF
 
-# 7. Copy Bundled Flake
-echo "Copying bundled upstream Nomarchy flake from $NOMARCHY_REPO..."
-cp -rL "$NOMARCHY_REPO" /mnt/etc/nixos/nomarchy
-chmod -R u+w /mnt/etc/nixos/nomarchy
-
 # 8. Version Control
 cd /mnt/etc/nixos/
 git init