Add a README so I don't forget how this thing works

Author: sidoh

web2/README.md

@@ -0,0 +1,35 @@
+# Web UI
+
+This contains the web UI for espMH. The UI is written with the following stack:
+
+* Typescript
+* React
+* Tailwind
+* Shadcn/ui
+* esbuild
+
+It compiles everything into C++ header files which are copied to `dist` and included as a part of the platformio build process.
+
+## Development
+
+It _should_ be enough to install node v20+ and run:
+
+```bash
+npm run watch
+```
+
+This will continuously run the build as files change. When I develop, I typically also use the nodejs server:
+
+```bash
+PROXY_URL=http://hostname-of-your-hub node server.js
+```
+
+I do this only to proxy API requests to an actual ESP8266 running on my local network.
+
+### API Client
+
+The API client in `web2/api` is generated from the openapi spec using `openapi-zod-client`. Run it with this command:
+
+```bash
+openapi-zod-client ../docs/openapi.yaml -o ./api/api-zod.ts --with-description
+```

web2/server.js

@@ -4,7 +4,7 @@ const path = require('path');
 
 const app = express();
 const PORT = 3000; // You can change this to any port you prefer
-const PROXY_URL = 'http://10.133.8.88'; // Replace with your proxy URL
+const PROXY_URL = process.env.PROXY_URL || 'http://10.133.8.88'; // Replace with your proxy URL
 
 const proxyMiddleware = createProxyMiddleware({
   target: PROXY_URL,