Add browser client docs

[lixmal]

[Copilot]

Pull Request Overview

This PR adds comprehensive documentation for NetBird's Browser Client feature, which enables secure remote access to SSH and RDP resources directly from web browsers without requiring client software installation.

• Adds user-facing documentation explaining how to use the Browser Client for SSH and RDP connections
• Includes technical architecture documentation detailing the WebAssembly implementation and security model
• Updates navigation to include both new documentation pages

Reviewed Changes

Copilot reviewed 3 out of 9 changed files in this pull request and generated 2 comments.

File	Description
src/pages/how-to/browser-client.mdx	Complete user guide covering Browser Client usage, prerequisites, connection procedures, and troubleshooting
src/pages/about-netbird/browser-client-architecture.mdx	Technical documentation explaining the WASM architecture, protocol bridges, and network implementation
src/components/NavigationDocs.jsx	Navigation updates to include both new documentation pages in appropriate sections

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