feat: add time conversion scripts

pkgs/default.nix

@@ -17,6 +17,8 @@ let
     "github-notifications"
     "screenshare"
     "bootstrap"
+    "t2ts"
+    "ts2t"
   ];
   mkPackages = names: builtins.listToAttrs (map
     (name: {

pkgs/t2ts/default.nix

@@ -0,0 +1,9 @@
+{ writeShellApplication }:
+
+writeShellApplication {
+  name = "t2ts";
+  runtimeInputs = [ ];
+  text = ''
+    date -d"$1" +%s
+  '';
+}

pkgs/ts2t/default.nix

@@ -0,0 +1,9 @@
+{ writeShellApplication }:
+
+writeShellApplication {
+  name = "ts2t";
+  runtimeInputs = [ ];
+  text = ''
+    date -d @"$1" 2>/dev/null || date -r "$1"
+  '';
+}