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/capitalize.ts

@@ -1,6 +1,6 @@
 export function capitalize(str: string): string {
   return str
-    .split(' ')
+    .split(" ")
     .map((word) => word.charAt(0).toUpperCase() + word.slice(1))
-    .join(' ');
+    .join(" ");
 }