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/components/EncryptionHelp.tsx

@@ -1,4 +1,4 @@
-import { VStack } from './core/Stacks';
+import { VStack } from "./core/Stacks";
 
 export function EncryptionHelp() {
   return (