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

@@ -1,5 +1,7 @@
-{:main       pocketbook.todomvc
- :output-to  "example/todomvc/js/main.js"
- :output-dir "example/todomvc/js/out"
- :asset-path "js/out"
- :optimizations :none}
+{:main           pocketbook.todomvc
+ :output-to      "example/todomvc/js/main.js"
+ :output-dir     "example/todomvc/js/out"
+ :asset-path     "js/out"
+ :optimizations  :none
+ :preloads       []
+ :browser-repl   false}