fix: resolve 3 assigned issues for jonathanayubausara-a11y (#459, #463, #464)

[jonathanayubausara-a11y]

Summary

This PR addresses 3 issues assigned to @jonathanayubausara-a11y in the Stellar Wave program.

Issue #459 (P3): WalletModal detection re-runs on every render

• Problem: detectInstalledWallets in WalletModal ran on every render even though window.ethereum cannot change between renders.
• Fix: Wrapped wallet detection in useMemo with an empty dependency array, so it runs only once on mount.
• Files: src/components/WalletModal.tsx

Issue #463 (P2): Add unit tests for qrCodeSecurity

• Problem: src/utils/security/qrCodeSecurity.ts had insufficient test coverage.
• Fix: Added comprehensive test cases covering:
  • Phishing URL detection
  • Deep-link validation (ethereum:, wc:, ftp:)
  • Unsafe protocol blocking (vbscript:, javascript:, data:, blob:)
  • Whitespace trimming
  • Allowed host matching (exact and subdomain)
  • URL length boundary cases
  • Empty input after trimming
  • Uppercase protocol handling
  • Suspicious domain warnings
  • getDisplaySafeUrl edge cases (empty input, exact max length, truncation)
• Added jest mock for PhishingProtection to isolate tests
• Files: src/utils/security/__tests__/qrCodeSecurity.test.ts

Issue #464 (P2): Add unit tests for useCurrencyConverter

• Problem: src/hooks/useCurrencyConverter.ts had no test file despite touching rate fetching, caching, and storage.
• Fix: Created comprehensive test suite with 24 tests covering:
  • Initial state (loading, null rate)
  • Successful ETH/USD rate fetch
  • HTTP error handling (429 status)
  • Network failures with localStorage cache fallback
  • Fresh cache reuse (<60 seconds)
  • Stale cache refresh (>60 seconds)
  • Storage re-hydration on mount
  • Conversion functions (convertEthToUsd, formatEthPrice, formatUsdPrice)
  • Refetch functionality with error handling
  • Auto-refresh interval setup and cleanup
  • Edge cases (missing/null/undefined/malformed responses)
  • Proper fake timer cleanup in beforeEach/afterEach
• Files: src/hooks/__tests__/useCurrencyConverter.test.ts (new)

Verification

• All 46 new/enhanced tests pass
• useMemo properly prevents re-computation on re-renders
• qrCodeSecurity tests cover phishing, deep-links, edge cases
• useCurrencyConverter tests cover fetching, caching, conversion

closes #459
closes #463
closes #464

[drips-wave]

@jonathanayubausara-a11y Great news! 🎉 Based on an automated assessment of this PR, the linked Wave issue(s) no longer count against your application limits.

You can now already apply to more issues while waiting for a review of this PR. Keep up the great work! 🚀

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