devShells: make all shells inherit from default shell

Currently, important tools from the default shell are lost as soon as select-shell is used to switch to another shell. select-shell itself, for example is missing, which makes it impossible to switch back to another shell.

pkgs/clan-app/flake-module.nix

@@ -6,6 +6,7 @@
       pkgs,
       lib,
       system,
+      self',
       ...
     }:
     if lib.elem system lib.platforms.darwin then
@@ -14,6 +15,7 @@
       {
         devShells.clan-app = pkgs.callPackage ./shell.nix {
           inherit (config.packages) clan-app webview-ui;
+          inherit self';
         };
         packages.clan-app = pkgs.python3.pkgs.callPackage ./default.nix {
           inherit (config.packages) clan-cli webview-ui;

pkgs/clan-app/shell.nix

@@ -11,6 +11,7 @@
   gtk4,
   libadwaita,
   webview-ui,
+  self',
 }:
 
 let
@@ -27,6 +28,9 @@ let
 in
 mkShell {
   inherit (clan-app) nativeBuildInputs;
+
+  inputsFrom = [ self'.devShells.default ];
+
   buildInputs =
     [
       ruff