feat: add multi-wallet support and Lighthouse CI (#343, #344)

[devJaja]

Summary

Closes OlaGreat#343 — Multi-wallet support
Closes OlaGreat#344 — Lighthouse CI for frontend performance

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OlaGreat#343 — Multiple wallet connections

New file: frontend/src/lib/wallet-adapters.ts

• WalletAdapter interface with a consistent connect(): Promise<string> API
• Adapters for Freighter, Albedo (window.albedo), and Lobstr (window.lobstr)
• getAvailableWallets() detects installed wallets at runtime; graceful fallback when none found

Modified: frontend/src/components/wallet-connect.tsx

• Dynamic wallet selector — renders a button per detected wallet
• Shows install prompt when no wallets are available
• Persists chosen wallet ID + address in localStorage for session restore

Modified: frontend/src/lib/stellar.ts

• Re-exports wallet utilities so callers can import from a single module

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OlaGreat#344 — Lighthouse CI

New file: lighthouserc.js

• Thresholds: performance ≥ 0.7, LCP ≤ 4s, FCP ≤ 3s, CLS ≤ 0.25, TBT warn at 600ms
• Uploads results to temporary public storage

Modified: .github/workflows/frontend.yml

• New lighthouse job runs on PRs only
• Fails CI on breached error-level assertions
• Uses LHCI_GITHUB_APP_TOKEN secret for PR comments

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Also fixed

• Pre-existing React hooks-rules violations in profile-card.tsx that were already breaking the build