Run oxfmt across repo, add format script and ignore config

Format all non-generated files with oxfmt via `vp fmt`. Add
.oxfmtignore to skip bindings/ and wasm-pack output. Add npm
format script and update DEVELOPMENT.md docs.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src-web/lib/scopes.ts

@@ -1,3 +1,3 @@
 export function isSidebarFocused() {
-  return document.activeElement?.closest('.x-theme-sidebar') != null;
+  return document.activeElement?.closest(".x-theme-sidebar") != null;
 }