Add Linux/Windows variants for VS Code shortcuts

[niklasmarderx]

What

The VS Code shortcuts in src/data/shortcuts.ts currently show macOS key combinations. Add Linux/Windows variants so users on those platforms see the correct shortcuts.

Why

Most developers use Linux or Windows. Showing Cmd+Shift+P when they need Ctrl+Shift+P is confusing.

How

1. Open src/data/shortcuts.ts
2. Look at the VS_CODE_SHORTCUTS collection
3. Add keysLinux? and/or keysWindows? fields to the Shortcut interface
4. For each VS Code shortcut, add the Linux/Windows equivalent (usually Cmd → Ctrl)
5. Update the UI to show the right keys based on the user's OS (navigator.platform)

Reference

VS Code Keyboard Shortcuts