Fix/transaction idempotency

[Muyideen-js]

Closes #26

Summary

Closes #[issue number]

Replace the stub StepDeposit component in the sponsor onboarding wizard with a fully functional deposit flow. Sponsors completing the 4-step onboarding can now actually deposit USDC — amount input with $10 minimum validation, unsigned XDR fetched from the API, signed via Freighter, submitted on-chain, and a success state with a Stellar Expert link. On success, onboarding is marked complete and the sponsor is navigated to the dashboard.

This repo is for the React web app only

This app targets sponsors, vendors, and mentors. It does NOT serve learners. Learner features belong in StepFi-App.

• Changes are inside src/
• No Rust, Soroban, or contract code
• No React Native or Expo-specific code
• No hardcoded hex color values (Tailwind classes only)
• All icons from lucide-react
• No API calls directly in page files (uses services/ layer)

Type of change

• Bug fix
• New page or component
• Service layer addition
• Styling or responsive fix
• Accessibility improvement
• Performance improvement

Testing

• npm run build — 0 errors
• npm run lint — 0 errors
• npm test — 36 tests passed, 0 failures
• Mobile viewport (375px) tested
• Browser console checked

Context files reviewed

• context/architecture-context.md
• context/code-standards.md
• context/progress-tracker.md updated

---

What changed

src/pages/SponsorOnboarding.tsx — Replaced the StepDeposit stub (lines 267–316) with a real deposit flow:

Feature	Implementation
Amount input	Numeric input with $10 minimum validation, inline error messaging (aria-invalid, role="alert")
XDR fetch	sponsorsService.deposit(amount) returns UnsignedTransaction<DepositPreview>
Freighter signing	Delegated to the existing useTransaction hook which calls @stellar/freighter-api's signTransaction
Submission	transactionsService.submit(signedXdr, 'deposit') posts to POST /transactions/submit
Success state	Card showing deposit amount, transaction hash, and a clickable Stellar Expert link
Onboarding completion	onComplete fires after deposit success → sets onboardingComplete: true → navigates to /sponsors
Error state	Inline error card using the same pattern as the Sponsors dashboard
Disconnected state	"Connect Freighter Wallet" button with download link + GrantFox fallback

All patterns mirror the existing deposit flow in src/pages/Sponsors.tsx — useTransaction, useToast, invalidatesubtree.pool, and the success card layout.

Acceptance criteria met

• Deposit amount input with $10 minimum validation
• Unsigned XDR fetched from API
• XDR signed via Freighter
• Signed XDR submitted
• Success state shown with Stellar Expert link
• Onboarding marked complete after successful deposit

Files changed

File	Change
src/pages/SponsorOnboarding.tsx	Replaced StepDeposit stub with full deposit flow (+ 5 new imports)