[UI/UX] Better empty-state guidance when no wallet is detected

[nanaf6203-bit]

Problem Statement

When no injected wallet is present, the page shows a generic "Connect Wallet" CTA. Users without MetaMask don't realise WalletConnect or Coinbase Wallet options exist.

Acceptance Criteria

• New empty state copy that lists all viable options (injected, WalletConnect QR, Coinbase)
• Each option has its own click handler
• "What is a wallet?" expandable intro for newcomers
• A Lighthouse a11y pass on the empty state

Implementation Notes

Educate rather than over-prompt. Use existing WalletConnector props.

Files Likely Affected

• src/components/WalletDisconnectedView.tsx
• src/components/OnboardingTour.tsx (link to new users)

Difficulty / Effort

• Difficulty: Easy
• Effort: T-Shirt M

Labels

ux, priority:medium, area:onboarding