chore: Move to Typescript (#2783)

This PR moves the entire project to Typescript. Due to the ~1000 ignores this will lead to a messy codebase for a while, but the churn is worth it – all of those ignore comments are places that were never type-safe previously.

closes #1282

app/env.ts

@@ -0,0 +1,11 @@
+import { PublicEnv } from "../shared/types";
+
+declare global {
+  interface Window {
+    env: PublicEnv;
+  }
+}
+
+const env = window.env;
+
+export default env;