Initial commit: homelab dashboard

Elixir + Phoenix dashboard displaying public and internal homelab
services. Internal services are shown only when the request originates
from the local network, detected server-side via conn.remote_ip with
Traefik trusted as a proxy (RemoteIp plug).

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

.formatter.exs

@@ -0,0 +1,5 @@
+[
+  import_deps: [:phoenix],
+  plugins: [Phoenix.LiveView.HTMLFormatter],
+  inputs: ["*.{heex,ex,exs}", "{config,lib,test}/**/*.{heex,ex,exs}"]
+]