feat(app): live transaction-count hint on transfer/withdraw amounts

[Patrick-Ehimen]

🚀 What’s this PR do?

Shows how many on-chain transactions an amount needs inline, as the user types, in the transfer and withdraw tabs only when that number is greater than one.

#436 already shows this figure in the confirmation dialog, i.e. after the user commits. This adds the part #386 describes as "updated whenever the input is changed by the user", so a split is visible while the amount can still be adjusted.

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📎 Related issues

Refs #386 not Closes, since #436 may already satisfy it in your view. Happy to close this if so.

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🧠 Context

Reuses the existing PrivatePool.estimate(amount) call, so the inline hint and the dialog can't disagree.

• Debounced 300ms otherwise one estimate per digit.
• Only shown when txCount > 1, per the issue.
• Out-of-order responses discarded by sequence number; a slow estimate must not describe an amount already changed.
• Recomputed on pool:selected (estimate is pool-specific) and wallet:ready (an amount typed before connecting is skipped for want of a wallet).
• Cleared on successful submit the field is reset programmatically and fires no input event.
• Best-effort like txCountRow: a failed estimate clears the hint rather than raising.

Note: txCountRow() guards with if (!txCount), so the dialog still renders "1 transaction" for single-transaction ops, which #386 asks to suppress. Left untouched as out of scope say the word and I'll align it.

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✅ Required Checklist

• I’ve read the contributing guide.
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• I’ve tested this locally, run .githooks/pre-push and provided test instructions for maintainers if needed
• I’ve added relevant docs or comments
• I’ve updated or created tests if needed

[Fantoni0]

Thanks for the contribution @Patrick-Ehimen 💯
I like the idea a lot, but I think some race conditions might happen.
My advice would be, rather than showing the number of steps a hint when configuring the transaction, you could show it in the confirm (app/js/confirm) modal. They already have access to the txCountRow() function, and you don't need to worry about calling ensureAppPool and avoid racing issues

[Fantoni0]

Thanks @Patrick-Ehimen
I was checking the deployed version on main, and noticed we already show a transaction-count hint on the confirm modal:

So not sure this PR would be adding anything else on this aspect :(
That being said, I think your changes for hardening the pool session are good and can still be merged. If you could please:

• Remove the html hints.
• Any logic related to transaction count/hints that is no longer needed
• Take a look to navigation.js, I think it could also use the pendingSession guard (on the disconect function we call closeAppPool but a createAppPool might already be running)

I think we can still merge this 🙌