refactor: add SystemStats singleton + nova-stats daemon for cpu/mem polling

flake.nix

@@ -32,6 +32,7 @@
         projectRootFile = "flake.nix";
         programs.nixfmt.enable = true;
         programs.qmlformat.enable = true;
+        programs.rustfmt.enable = true;
       };
       forAllSystems =
         fn:
@@ -53,9 +54,14 @@
             withX11 = false;
             withI3 = false;
           };
+          nova-stats = pkgs.callPackage ./nix/stats-daemon.nix { };
         in
         rec {
-          nova-shell = pkgs.callPackage ./nix/package.nix { quickshell = qs; };
+          inherit nova-stats;
+          nova-shell = pkgs.callPackage ./nix/package.nix {
+            quickshell = qs;
+            inherit nova-stats;
+          };
           nova-shell-cli = pkgs.runCommand "nova-shell-cli" { nativeBuildInputs = [ pkgs.makeWrapper ]; } ''
             mkdir -p $out/bin
             makeWrapper ${qs}/bin/quickshell $out/bin/nova-shell \
@@ -65,6 +71,21 @@
         }
       );
 
+      devShells = forAllSystems (
+        { pkgs, ... }:
+        {
+          default = pkgs.mkShell {
+            packages = with pkgs; [
+              cargo
+              rustc
+              rust-analyzer
+              clippy
+              rustfmt
+            ];
+          };
+        }
+      );
+
       checks = forAllSystems (
         { pkgs, treefmt-eval }:
         {