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/package.json

@@ -1,7 +1,7 @@
 {
   "name": "@yaakapp/app",
-  "private": true,
   "version": "1.0.0",
+  "private": true,
   "type": "module",
   "scripts": {
     "dev": "vp dev --force",