Persist WalletConnect session across page reloads

[Kingsman-99]

Description

adapters/walletconnect.ts establishes a WalletConnect session but does not persist it to localStorage. Every page reload forces the user to reconnect by scanning a QR code, degrading the user experience.

Acceptance Criteria

• On successful connection, the session topic and relay URL are persisted to localStorage
• On adapter initialisation, a stored session is restored automatically if it has not expired
• disconnect() clears the persisted session data
• Unit tests pass

Context

• Target file: src/adapters/walletconnect.ts
• Use the WalletConnect session expiry timestamp to determine validity on restore