feat: add jetton processing

[Kaladin13]

Closes #700

[github-actions]

To fix the formatting issues:

1. Install necessary dependencies: npm ci
2. Then, run this command:

npx remark -o --silent --silently-ignore payments/jettons.mdx 

[Kaladin13]

Merge only after ton-org/docs-examples#7

[github-actions]

Thanks for the PR. In payments/jettons.mdx, several suggestions to address terminology, tone, and safety callouts—please apply the inline suggestions.

[anton-trunov]

/review

[github-actions]

Thanks for the update. In payments/jettons.mdx, there are several suggestions to tighten the safety callouts; please apply the inline suggestions.