Expand web test coverage for wallet flows dashboard mapping and analytics route

[Purity-Euphemia]

Closes #195 # PR 204: Expand web test coverage for wallet flows, dashboard mapping, and analytics routes

This PR adds focused test coverage for key web logic in the VeilLend web app. It improves confidence around wallet connection flows, dashboard data mapping, and campaign analytics route behavior.

What's included

• Added a new hook test for useStellarWallet to verify:
  • wallet initialization state
  • successful Freighter connection and auth session creation
  • disconnect behavior and auth session cleanup
  • connect failure handling
• Extended WalletConnect coverage to verify:
  • Freighter install prompt when the wallet extension is missing
  • connect button disabled state during loading
• Expanded dashboard mapping coverage in fetchDashboardData to validate:
  • empty indexer responses
  • portfolio totals and activity mapping
• Added analytics behavior coverage for trackCampaignEvent fallback path when navigator.sendBeacon is unavailable
• Hardened the analytics helper to safely handle a non-promise fetch fallback

Files changed

• veilend-web/src/__tests__/useStellarWallet.test.tsx
• veilend-web/src/__tests__/wallet.test.tsx
• veilend-web/src/__tests__/dashboardData.test.ts
• veilend-web/src/__tests__/campaignAnalytics.test.ts
• veilend-web/src/lib/campaignAnalytics.ts

Test validation

Run the following in the veilend-web workspace:

cd veilend-web
npm test -- --run src/__tests__/wallet.test.tsx src/__tests__/dashboardData.test.ts src/__tests__/campaignAnalytics.test.ts src/__tests__/useStellarWallet.test.tsx

Result: 21 passed across the targeted test files.

[Cedarich]

@Purity-Euphemia