Replace command-not-found with nix-index

flake.nix

@@ -23,9 +23,13 @@
       url = "github:robn/sasl2-oauth";
       flake = false;
     };
+    nix-index-database = {
+      url = "github:Mic92/nix-index-database";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
   };
 
-  outputs = { self, nixpkgs, agenix, ... }@inputs:
+  outputs = { self, nixpkgs, agenix, nix-index-database, ... }@inputs:
     let
       system = "x86_64-linux";
 
@@ -36,7 +40,11 @@
     in {
       nixosConfigurations.panacea = lib.nixosSystem {
         inherit system;
-        modules = [ (import ./configuration.nix) agenix.nixosModules.age ];
+        modules = [
+          (import ./configuration.nix)
+          agenix.nixosModules.age
+          nix-index-database.nixosModules.nix-index
+        ];
         specialArgs = { inherit inputs; };
       };