Auto-sync services from homelab repo via GenServer

ServicesSync polls ~/dev/homelab every 5 minutes: runs git pull, then
re-parses ansible/roles/traefik/defaults/main.yml to derive public and
internal service lists. Services with public_host are shown publicly;
others require internal network access. PageController now delegates to
ServicesSync instead of hardcoded module attributes.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

mix.exs

@@ -63,7 +63,8 @@ defmodule HomelabDashboard.MixProject do
       {:jason, "~> 1.2"},
       {:dns_cluster, "~> 0.2.0"},
       {:bandit, "~> 1.5"},
-      {:remote_ip, "~> 1.2"}
+      {:remote_ip, "~> 1.2"},
+      {:yaml_elixir, "~> 2.9"}
     ]
   end