Split Amount Rounding Discrepancy Handler and Warning

[Kingsman-99]

Description

Converting floating-point percentage splits to integer stroops produces rounding errors where the sum of recipient amounts is one or two stroops less than the invoice total, causing contract rejections that confuse users. The frontend must detect and resolve these discrepancies before sending the transaction.

Technical Context

src/hooks/useSplitCalculator.ts adds a resolveRounding function that converts each percentage to stroops, sums them, and assigns any remainder stroops to the first recipient. src/components/invoice/SplitSummaryCard.tsx shows a soft warning when a rounding adjustment was applied, explaining how many stroops were redistributed. src/lib/stellar.ts validates the resolved amounts sum exactly to the invoice total in stroops before building the transaction.

Acceptance Criteria

• The resolveRounding function always produces amounts that sum to the invoice total in stroops
• A warning label appears when a rounding adjustment of one or more stroops is applied
• The warning label explains which recipient received the adjustment and by how many stroops
• The transaction is blocked from submission if the amounts do not sum correctly after resolution
• Unit tests in src/__tests__/useSplitCalculator.test.ts cover the rounding logic for 3-, 7-, and 11-recipient splits
• All CI checks (npm test, npm run build, ESLint/TypeScript) pass and the branch has no merge conflicts

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[Malcolm-Wander]

@Malcolm-Wander has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

Hello maintainer,I’d love to work on this issue please,I promise to do a good and swift job..thank you.

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[Thomson-dev]

@Thomson-dev has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

pls can I handle this task

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[Peaostrel]

@Peaostrel has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

i can handle this quickly

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[Almikefred]

@Almikefred has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

Hi maintainer assign me this issue

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[drips-wave]

Congratulations, @Almikefred! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on July 30, 2026.

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