Add Cloud Agent environment config for Server component

[kebkfdbbd]

Summary

Sets up a reproducible development environment for the cross-platform Server component on Linux Cloud Agents.

The main product (GitHub Copilot for Xcode host app, ExtensionService, EditorExtension, Core/Tool Swift packages) is macOS/Xcode-only — it targets .macOS(.v13) and depends on AppKit/SwiftUI/XPC, Sparkle, CGEventOverride, KeyboardShortcuts, etc. It cannot be built or run on a Linux agent (no Xcode / macOS SDK).

The Server directory is a Node/TypeScript/webpack project that builds the embedded web UIs (the Monaco-based diff viewer and the xterm-based terminal) used inside the app's WKWebViews. This part builds and runs on Linux.

Changes

• Add .cursor/environment.json:
  • install: cd Server && npm install --force && npm run build (--force is needed because Server/package.json lists darwin-only @github/copilot-language-server-* binaries as hard deps, which fail EBADPLATFORM on Linux; they're runtime binaries for the packaged app and aren't needed to build the web bundles).
  • terminals: serves the built Server/dist on port 8099 for previewing the components.

Verification

• npm install --force and npm run build (webpack) complete successfully, emitting dist/diffView/diffView.js (Monaco) and dist/terminal/terminal.js (xterm).
• Served dist and confirmed both components render in Chrome with sample data driven through their public JS APIs (window.DiffViewer.init(...) and window.initializeTerminal()/writeToTerminal(...)).