Refactor ICE Restart Demo

[RafaelPChequer]

Description

This PR introduces significant improvements to the restart-ice example, focusing on streamlining the development and testing workflow. Key changes include:

• SDK Build Instructions: Detailed documentation on how to generate the SDK bundle (signalwire.min.js) from the repository root and link it to the example.
• UI Overhaul: Enhanced layout for the credentials form (Space, Project, Token) and the call control section (Audio/Video/AutoAnswer).
• Data Persistence: Implementation of localStorage to save credentials and configurations, preventing the need to re-enter data after a page refresh.
• ICE Restart Functionality: Added UI buttons and logic to force or automate ICE Restarts (essential for WebRTC connectivity testing).
• Enhanced Logging: Improved log area for better real-time debugging and session tracking.

Type of Change

• Bug fix
• New feature
• Breaking change
• Documentation update
• Code cleanup / refactor

Related Issues

Relates to improving Developer Experience (DX) across the Relay SDK JavaScript examples.

Testing

Manual testing was performed following the new build workflow:

1. Built the SDK via npm run build within the packages/js directory.
2. Copied the output index.min.js to examples/restart-ice/signalwire.min.js.
3. Ran a local web server using python3 -m http.server.
4. Validated JWT Token generation directly through the UI.
5. Successfully established calls and verified field persistence via localStorage.

• Added/updated unit tests
• Tested manually
• Tested with live SignalWire credentials (if applicable)

Checklist

• I have read the [CONTRIBUTING](https://www.google.com/search?q=CONTRIBUTING.md) guidelines
• My code follows the project's style guidelines
• I have added tests for my changes (if applicable)
• I have updated documentation (if applicable)
• All existing tests pass

Additional Notes

The interface now utilizes Bootstrap 4 to ensure a responsive layout. A troubleshooting note regarding 3rd-party cookie blocking was added, as it can affect localStorage when the file is opened via the file:// protocol; using a local web server is explicitly recommended.