feat: add devshell and improve input handling of cells

pass system to cells and their flake.nix inputs

lib/core/loader.nix

@@ -22,7 +22,13 @@
         cell = cells // {__cr = [cellName cellBlock.name];};
         additionalInputs =
           if l.pathExists cellP.flake
-          then (callFlake (builtins.dirOf cellP.flake) {root.parent = inputs;}).outputs
+          then
+            (callFlake (builtins.dirOf cellP.flake) {
+              root = {
+                parent = inputs;
+                system = system;
+              };
+            }).outputs
           else {};
       in
         importSignatureFor system cell cells additionalInputs;

lib/utils/import-signature.nix

@@ -28,7 +28,7 @@
         inherit self;
         cells = deSystemize system cells;
       };
-    inherit cell;
+    inherit cell system;
   };
 in {
   inherit deSystemize createImportSignature;