flake: add packages to flake and add hydra build jobs

flake.nix

@@ -2,7 +2,15 @@
   inputs = {
     nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
   };
-  outputs = { nixpkgs, ... }: {
+  outputs = { self, nixpkgs, ... }: let
+    pkgs = import nixpkgs {
+      overlays = [
+        (import ./pkgs/overlay.nix)
+      ];
+      system = "x86_64-linux";
+    };
+    system = "x86_64-linux";
+  in {
     colmena = {
       meta = {
         nixpkgs = import nixpkgs {};
@@ -54,5 +62,20 @@
 
       web-2 = { ... }: {};
     };
+
+    packages.x86_64-linux = {
+      inherit (pkgs)
+        anycast_healthchecker
+        flask-excel
+        iot-data
+        pyexcel-xlsx
+        pyexcel-webio
+        uptimestatus
+        wetter;
+    };
+
+    hydraJobs = {
+      inherit (self) packages;
+    };
   };
 }