refactor(firmware): remove the retired simulation workflow

Remove the retired simulator workspace member, dependencies, workflow
and documentation. Keep the shared flight and hardware crates.

Validation: retirement prefix host check, command-dispatch tests and
book build.

flake.nix

@@ -17,12 +17,6 @@
         system:
         let
           pkgs = nixpkgs.legacyPackages.${system};
-          python = pkgs.python3.withPackages (
-            pythonPackages: with pythonPackages; [
-              pymavlink
-              pyserial
-            ]
-          );
         in
         {
           default = pkgs.mkShell {
@@ -35,7 +29,7 @@
               pkgs.shfmt
               pkgs.nixfmt
               pkgs.taplo
-              python
+              pkgs.python3
             ];
           };
         }