Add VitePress documentation site setup

Introduces VitePress configuration and theme files for documentation, updates the GitHub Pages workflow to build and deploy the new docs, and updates .gitignore for VitePress and Node artifacts. Adds necessary dependencies and scripts to package.json, and updates the ONVIF client example README title.

.vitepress/theme/custom.css

@@ -0,0 +1,4 @@
+
+.VPSidebarItem.level-1 {
+  font-weight: 700;
+}

.vitepress/theme/index.ts

@@ -0,0 +1,5 @@
+import DefaultTheme from 'vitepress/theme';
+import "@catppuccin/vitepress/theme/mocha/mauve.css";
+import './custom.css';
+
+export default DefaultTheme;