feat(declib): initial mastodon bot experiment

No default.nix yet, just for development.

Change-Id: Ib8bd0057d697fecd083d5961e635c770b7638e08
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10803
Reviewed-by: Profpatsch <mail@profpatsch.de>
Tested-by: BuildkiteCI

users/Profpatsch/shell.nix

@@ -61,6 +61,8 @@ pkgs.mkShell {
     pkgs.pkg-config
     pkgs.fuse
     pkgs.postgresql
+    pkgs.nodejs
+    pkgs.ninja
   ];
 
   WHATCD_RESOLVER_TOOLS = pkgs.linkFarm "whatcd-resolver-tools" [
@@ -70,6 +72,8 @@ pkgs.mkShell {
     }
   ];
 
+  # DECLIB_MASTODON_ACCESS_TOKEN read from `pass` in .envrc.
+
   RUSTC_WRAPPER =
     let
       wrapperArgFile = libs: pkgs.writeText "rustc-wrapper-args"