Add helper for displaying sell proceeds estimate before confirmation

[Chucks1093]

Summary
Users see the final sell proceeds only after the transaction is built, making it impossible to evaluate the trade before committing. A pre-confirmation estimate helper that computes and displays approximate proceeds gives users the information needed to decide.

Scope

• add a helper that computes an estimated sell proceeds amount from the current supply and sell quantity
• display the estimate in the sell flow before the confirmation step
• label the estimate clearly as approximate

Acceptance Criteria

• a proceeds estimate is shown before the user reaches the sell confirmation step
• the estimate is labeled as approximate
• if the estimate cannot be computed the UI shows a cannot estimate message

Contributor coordination: if you pick this up, reach out in Telegram for updates or clarification: https://t.me/accesslayerorg

[sochima2]

@sochima2 has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

can i work on this

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[victor62-art]

@victor62-art has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

pls assign me this issue

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[michaelvic123]

@michaelvic123 has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

please assign this issue to me

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[drips-wave]

Congratulations, @victor62-art! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 2, 2026.

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