feat: add customizable keyboard shortcuts with Options tab

- Add Options tab in popup for key customization
- Implement dynamic key binding (Start/Stop/Paste)
- Add storage permission for persisting key settings
- Improve UI with header, toggle, and better styling
- Update README with demo video and better formatting

Update readme file

ADD: AutoSend functionality

Update README.md

- Change center tag to div tag and add align decorator with center value to center the image
- Fix typo

Initial Commit