refactor(templates/vanilla): remove default.nix boilerplate, use import-tree directly

Author: DivitMittal

templates/vanilla/flake.nix

@@ -3,11 +3,10 @@
 
   outputs = inputs: let
     inherit (inputs.flake-parts.lib) mkFlake;
-    specialArgs.customLib.scanPaths = path: [(inputs.import-tree.matchNot ".*/default\\.nix" path)];
   in
-    mkFlake {inherit inputs specialArgs;} ({inputs, ...}: {
+    mkFlake {inherit inputs;} ({inputs, ...}: {
       systems = import inputs.systems;
-      imports = [./flake];
+      imports = [(inputs.import-tree ./flake)];
     });
 
   inputs = {