Added keyboard shortcut for code selection

[hemanth5055]

Summary

I've added a keyboard shortcut (Alt+T / Option+T) to activate the code selection mode in the extension.

Details

• Defined a new command enable-code-selection in manifest.json
• Assigned the shortcut key for both default and macOS platforms (Alt maps to Option on macOS)
• Added a command listener in the background script to trigger the picker

Please review the changes and let me know if there's anything I can improve or refine. 🙂
closes #14

[dineshsutihar]

Hey @hemanth5055,

Thanks a lot for the PR, I really appreciate your work on adding the Alt+T shortcut! 🙌

However, I realized that Alt+T can conflict with some browser behavior (especially the Tools menu on Chrome/Edge). To ensure better cross-platform compatibility and avoid accidental browser interactions, I’ve decided to switch to a safer and more ergonomic shortcut.

🔄 New shortcut for Translate → Alt + Shift + A (Please use this now)

You only need to update the Translate shortcut for now, we’ll add others like Explain and Settings later.

Also, please explicitly include the shortcut for macOS as well. Here’s the updated manifest.json snippet:

"translate": {
  "suggested_key": {
    "default": "Alt+Shift+A",
    "mac": "Alt+Shift+A"
  },
  "description": "Translate selected text"
}

[dineshsutihar]

LGTM