chore: add build:watch script and document react-bwin dev workflow

CONTRIBUTING.md

@@ -19,3 +19,30 @@ Create a `.env.local` to set the default minimum width/height (in pixels) for a
 VITE_DEFAULT_SASH_MIN_WIDTH=100
 VITE_DEFAULT_SASH_MIN_HEIGHT=100
 ```
+
+## Working with react-bwin
+
+[`react-bwin`](https://github.com/bhjsdev/react-bwin) consumes bwin's **built**
+output (`dist/bwin.js`), not `src/`. To develop both together (assuming the
+repos are siblings), link them and rebuild bwin on save:
+
+In `react-bwin`, symlink to your local bwin checkout (don't commit this):
+
+```sh
+pnpm add bwin@link:../bwin
+```
+
+In `bwin`, regenerate `dist/bwin.js` on every change:
+
+```sh
+pnpm build:watch
+```
+
+In `react-bwin`, start the dev server (hot-reloads through the symlink):
+
+```sh
+pnpm dev
+```
+
+`pnpm dev` still works in bwin alongside `build:watch` if you want bwin's own
+dev pages running at the same time.

package.json

@@ -33,6 +33,7 @@
   "scripts": {
     "dev": "vite --port 7100",
     "build": "vite build",
+    "build:watch": "vite build --watch",
     "test": "vitest",
     "format": "prettier --write .",
     "format:check": "prettier --check .",