fix: disable browser REPL preload that blocks script loading

The default ClojureScript build includes clojure.browser.repl.preload
which tries to connect to a REPL server on load. When no REPL is
running, this blocks the goog.require chain and the app never
initializes (stuck on "Loading from local store").

Set :preloads [] and :browser-repl false in build.edn.

build.edn

@@ -2,4 +2,6 @@
  :output-to      "example/todomvc/js/main.js"
  :output-dir     "example/todomvc/js/out"
  :asset-path     "js/out"
- :optimizations :none}
+ :optimizations  :none
+ :preloads       []
+ :browser-repl   false}