fix(llm): 🐛 fix long Memo Tag issue on Cardano

[thesan]

✅ Checklist

• npx changeset was attached.
• Covered by automatic tests.
• Impact of the changes:
  • ...

📝 Description

Truncate Cardano memos in the input to prevent the transaction validation errors.
(Follow up to #8340 and #8604).

Screen.Recording.2024-12-05.at.11.59.52.mov

❓ Context

• LIVE-15161
• LIVE-15162

---

🧐 Checklist for the PR Reviewers

• The code aligns with the requirements described in the linked JIRA or GitHub issue.
• The PR description clearly documents the changes made and explains any technical trade-offs or design decisions.
• There are no undocumented trade-offs, technical debt, or maintainability issues.
• The PR has been tested thoroughly, and any potential edge cases have been considered and handled.
• Any new dependencies have been justified and documented.
• Performance considerations have been taken into account. (changes have been profiled or benchmarked if necessary)

[vercel]

The latest updates on your projects. Learn more about Vercel for Git ↗︎

4 Skipped Deployments

Name	Status	Preview	Comments	Updated (UTC)
ledger-live-github-bot	⬜️ Ignored (Inspect)	Visit Preview		Dec 6, 2024 0:29am
native-ui-storybook	⬜️ Ignored (Inspect)	Visit Preview		Dec 6, 2024 0:29am
react-ui-storybook	⬜️ Ignored (Inspect)	Visit Preview		Dec 6, 2024 0:29am
web-tools	⬜️ Ignored (Inspect)	Visit Preview		Dec 6, 2024 0:29am

[thesan]

TLDR I removed the last commit because I did one last test which went wrong and there's a minor bug on the backend.

If I send a memo with loads of emojies like 50👍 then maxLength will cut it to 32👍. It felt wrong to just use 2bytes per 👍 but it passes the backend doesn't report the "string or buffer length invalid" (like in LIVE-15162) so I assumed it was fine.
However when I actually sent the transaction it failed with the backend returning: API HTTP 400 https://cardano.coin.ledger.com/api/v1/transaction/submit. When reverting to truncateUtf8 it correctly truncate to 16👍 (which should fit in 64bytes).

This means that the backend validation is incorect it probably checks for the length of the string instead of the bytes size of the string (in most emojies get encoded in 2 characters).