ci: add npm audit check and fix all CI failures

- Bump vitest from ^1.6.0 to ^3.2.6 to resolve critical CVE (GHSA-5xrq-8626-4rwp) and high severity vulnerabilities
- Fix SorobanRpc → rpc namespace rename for @stellar/stellar-sdk v13 (useLedgerEntry, useSorobanContract, useTransaction)
- Fix StellarTomlResolver → StellarToml.Resolver.resolve for SDK v13 (useStellarToml)
- Fix useFreighter to use freighter-api v2 API (getPublicKey, getNetworkDetails instead of getAddress)
- Fix fee type in ContractCallOptions (number → string)
- Fix utils/index.ts parseAccountResponse for exactOptionalPropertyTypes and liquidity pool balances
- Fix broken import paths in utils.test.ts (../src/utils → ../utils)
- Fix unused imports and no-explicit-any lint errors across hooks and tests
- Fix useContractEvents.test.ts possibly undefined access

Closes #172

Author: DammyAji