Optimize bundle size + chunked builds + JIT loading

* Replaced AJV with other JSON schema library
* Turndown and Vim mode (very large) now only loaded when used
* Chunked builds with ESBuild

client/vim_loader.ts

@@ -0,0 +1,12 @@
+let vimModule: typeof import("@replit/codemirror-vim") | null = null;
+
+export async function loadVim() {
+  if (!vimModule) {
+    vimModule = await import("@replit/codemirror-vim");
+  }
+  return vimModule;
+}
+
+export function getVimModule() {
+  return vimModule;
+}