conky: split sane-battery-estimate out into its own program

hosts/common/programs/assorted.nix

@@ -801,6 +801,8 @@ in
 
     sane-die-with-parent.sandbox.enable = false;  #< it's a launcher; can't sandbox
 
+    sane-weather = {};
+
     screen.sandbox.enable = false;  #< tty; needs to run anything
 
     sequoia.sandbox.method = "bwrap";  # TODO:sandbox: untested

hosts/common/programs/conky/default.nix

@@ -1,5 +1,11 @@
 { pkgs, ... }:
 {
+  sane.programs.sane-battery-estimate = {
+    packageUnwrapped = pkgs.static-nix-shell.mkBash {
+      pname = "sane-battery-estimate";
+      srcRoot = ./.;
+    };
+  };
   sane.programs.conky = {
     sandbox.method = "bwrap";
     sandbox.net = "clearnet";  #< for the scripts it calls (weather)
@@ -11,18 +17,16 @@
     ];
     sandbox.whitelistWayland = true;
 
-    fs.".config/conky/conky.conf".symlink.target =
-      let
-        # TODO: make this just another `suggestedPrograms`!
-        battery_estimate = pkgs.static-nix-shell.mkBash {
-          pname = "battery_estimate";
-          srcRoot = ./.;
-        };
-      in pkgs.substituteAll {
-        src = ./conky.conf;
-        bat = "${battery_estimate}/bin/battery_estimate";
-        weather = "timeout 20 ${pkgs.sane-weather}/bin/sane-weather";
-      };
+    suggestedPrograms = [
+      "sane-battery-estimate"
+      "sane-weather"
+    ];
+
+    fs.".config/conky/conky.conf".symlink.target = pkgs.substituteAll {
+      src = ./conky.conf;
+      bat = "sane-battery-estimate";
+      weather = "timeout 20 sane-weather";
+    };
 
     services.conky = {
       description = "conky dynamic desktop background";

hosts/common/programs/conky/sane-battery-estimate

@@ -1,4 +1,3 @@
-#!/bin/sh
 #!/usr/bin/env nix-shell
 #!nix-shell -i bash