feat(tailscale): enable mesh networking across NixOS hosts

- enable Tailscale on Bob, Brain, Jeeves, and Rhapsody
- configure the Jeeves binary cache through Tailscale MagicDNS
- trust the existing workshop cache signing key

systems/portal-1/default.nix

@@ -7,8 +7,8 @@
 {
   imports = [
     inputs.disko.nixosModules.disko
-    "${inputs.self}/common/global"
     "${inputs.self}/users/richie"
+    "${inputs.self}/common/global"
     "${inputs.self}/common/optional/tailscale.nix"
     ./disk-config.nix
   ];