Avoid processing config when serving from overlay directory

[stelcodes]

Currently all requests for CSS/JS/whatever from the overlay directory cause the config to be loaded every time. This is wasteful and produces obnoxious log messages like:

18:18:52 INFO ⚡🐈 Rendering page:
{:nuzzle/get-config
 #function[nuzzle.generator/gen-get-config/get-config--5558],
 :nuzzle/index
 #{[:blog-posts] [:tags] [:coding-projects] [:educational-media]},
 :nuzzle/page-key [],
 :nuzzle/render-content #function[clojure.core/constantly/fn--5740],
 :nuzzle/title "Home",
 :nuzzle/url "/"}
18:18:52 INFO 🔨🐈 Building drafts
18:18:52 INFO 🔨🐈 Building drafts
18:18:52 INFO 🔨🐈 Building drafts
18:18:52 INFO 🔨🐈 Building drafts
18:18:53 INFO 🔨🐈 Building drafts
18:18:53 INFO 🔨🐈 Building drafts

Avoiding this is tricky. I probably need to try serving every page from the static directory ring middleware handler first and check if the status is a 400 or similar.