Run oxfmt across repo, add format script and docs

Add .oxfmtignore to skip generated bindings and wasm-pack output.
Add npm format script, update DEVELOPMENT.md for Vite+ toolchain,
and format all non-generated files with oxfmt.

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

packages/plugin-runtime/src/EventChannel.ts

@@ -1,4 +1,4 @@
-import type { InternalEvent } from '@yaakapp/api';
+import type { InternalEvent } from "@yaakapp/api";
 
 export class EventChannel {
   #listeners = new Set<(event: InternalEvent) => void>();