Avoid broken LiveView when rendered app with Render deployment URL.

[zorn]

Render always will deploy to https://flick-ysjm.onrender.com/ but the app is configured using PHX_HOSTNAME that points to rankedvote.app.

flick/config/runtime.exs

Line 55 in b6b099d

host = System.get_env("PHX_HOSTNAME") || "example.com"

When you visit using the Render URL the websocket LiveView does not function as expected.

It would probably be best if we detected an attempt to load the home page with said URL and redirect to the canonical one.