update flake to use fhs deno

.forgejo/workflows/deploy.yaml

···
           submodules: true
 
       - name: Run Lume Build
-        run: nix run nixpkgs#deno -- task prod
+        run: nix run . --impure -- task prod
 
       - name: Deploy
         uses: https://git.pyrox.dev/actions/pages-action@v3

flake.nix

···
   inputs = {
     nixpkgs.url = "github:nixos/nixpkgs/nixpkgs-unstable";
   };
-  outputs = { nixpkgs, ... }: let
+  outputs = { self, nixpkgs, ... }: let
       pkgs = import nixpkgs {
         allowUnfree = true;
       };
+      fhs = pkgs.buildFHSEnv {
+        name = "deno";
+        runScript = "deno";
+        targetPkgs = pkgs: [
+          pkgs.deno
+        ];
+      };
     in {
-    devShells.x86_64-linux.default = pkgs.mkShellNoCC {
+    packages.x86_64-linux = {
+      deno-fhs = fhs;
+      default = self.packages.x86_64-linux.deno-fhs;
+    };
+    apps.x86_64-linux = {
+      deno-fhs = {
+        type = "app";
+        program = pkgs.lib.getExe self.packages.x86_64-linux.default;
+      };
+      default = self.apps.x86_64-linux.deno-fhs;
+    };
+
+    devShells.x86_64-linux.default = pkgs.mkShell {
       buildInputs = [
-        pkgs.deno
+        fhs
         pkgs.just
         pkgs.caddy
         (pkgs.python3.withPackages (