Docs(readme): Add playground & Channel Logo

[jeff-tbd]

Self Checklist

• I wrote a PR title in English and added an appropriate label to the PR.
• I wrote the commit message in English and to follow the Conventional Commits specification.
• I wrote or updated documentation related to the changes. (or didn't have to)
• I wrote or updated tests related to the changes. (or didn't have to)
• I tested the changes in various browsers. (or didn't have to)
  • Windows: Chrome, Edge, (Optional) Firefox
  • macOS: Chrome, Edge, Safari, (Optional) Firefox
  • Android: Chrome, Samsung Internet
  • iOS: Safari, Chrome,

Related Issue

Summary

• Add Playground to Readme
• Add Channel Talk logo to Readme

Details

• CodeSandbox - React Demo
• Add Channel Talk logo
  • light mode
  • dark mode
• version update -> v1.1.5

Breaking change? (Yes/No)

• No

References

• https://codesandbox.io/p/devbox/ch-web-sdk-playground-xm8ls8
• https://github.com/pmndrs/jotai