Signature pad widget

[alkaChaudhary73]

PR Description
Added a new Signature Pad Widget that allows users to draw, clear, and attach their signatures directly from a ServiceNow Service Portal page.
This widget uses a native HTML5 <canvas> element with mouse and touch support (no external dependencies).
It includes clear and attach functionality and converts drawn signatures into Base64 PNG format for future attachment or storage use.

Pull Request Checklist

Overview

• I have read and understood the CONTRIBUTING.md guidelines
• My pull request has a descriptive title and includes this detailed description of the widget
• Only files relevant to the Signature Pad Widget are included
• A new branch has been created for this contribution

Code Quality

• The code is relevant to ServiceNow developers
• The widget demonstrates HTML5 Canvas usage within Service Portal
• The implementation is dependency-free and compatible with both mouse and touch inputs
• Code has been tested in a ServiceNow Service Portal environment

Repository Structure Compliance

• Placed under Client-Side Components/Widgets/Signature Pad Widget/
• Each snippet is contained within its own folder with descriptive naming
• Follows the organized structure required for repository contributions

Documentation

• Included a README.md file explaining:
  • Widget functionality
  • Usage instructions
  • Dependencies (none)
  • Future enhancements
• README includes example usage and developer notes

Restrictions

• No XML exports are included
• No sensitive or credential-related data is present
• PR scope is limited to the Signature Pad Widget functionality only

[am-shakeel]

Looks good