feat: add TypeScript to utils and code-split heavy components

[Markodiba]

• Add typescript ^5, @types/react ^18.3, @types/react-dom ^18.3 to frontend devDependencies and a typecheck (tsc --noEmit) script
• Add tsconfig.json with strict mode, allowJs/checkJs:false for incremental migration; moduleResolution: bundler for Vite compat
• Convert all 8 src/utils/ files from .js → .ts with full types: interfaces for ApiError, Transaction, SearchCriteria, ErrorEntry, VitalEntry, AnimationVariants; declare global Window extensions
• Add tsc --noEmit step to CI workflow (.github/workflows/test.yml)
• Convert AMMPoolBrowser, AccountRecovery, MultiSigTransactions, KYCForm, ComplianceDashboard, BackupSettings to React.lazy() in App.jsx; wrap each render site in <Suspense fallback={}>
• Add lazy-loading.test.js asserting no static imports exist for heavy components and lazy() declarations are present
• Add frontend/docs/typescript-migration.md with 8-phase plan for migrating remaining .jsx files to .tsx

closes #467
closes #468

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