docs: document build minifier and warn against editing www/ directly

website/README.md

@@ -17,6 +17,7 @@ The website handles incoming invitation links. When a user clicks a link like `s
 
 The website is 100% **Static HTML, CSS, and JS**. 
 - **Static i18n Compiler**: The site uses a lightweight, zero-dependency Node.js compiler (`build.js`) to parse dictionary files inside `/locales/` against a single source-of-truth template (`template.html`), outputting the fully deployable static folder to `/www/`.
+- **Build-time Minification**: `build.js` automatically minifies CSS and JS during compilation using a built-in state-machine tokenizer (no npm dependencies). Source files are written unminified — always edit source files, never the generated files in `www/`.
 - **Zero Backend**: No Node.js, PHP, or databases are required to host the compiled website.
 - **Zero Tracking**: All assets (fonts, icons) are self-hosted to prevent third-party tracking.
 - **Responsive**: Fully optimized for mobile with a native-feel hamburger menu.
@@ -68,3 +69,6 @@ sync.koalastuff.net {
    npx serve website/www
    ```
 3. To test the invitation flow locally, navigate to `http://localhost:5000/join.html#join:test-room:test-pass`.
+
+> [!IMPORTANT]
+> **Never edit files inside `website/www/` directly.** This directory is fully auto-generated by `build.js`. Always edit source files (`template.html`, `style.css`, `app.js`, `lang-init.js`, locale files in `locales/`) and re-run `node website/build.js` to apply changes. CSS and JS are minified during the build — editing minified files in `www/` will result in lost changes on the next build.