feat(ui): add interactive user onboarding tour via react-joyride (#599)

[Code-Paragon]

Summary

• Integrated react-joyride to implement an interactive 4-step user onboarding tour.
• Created <OnboardingTour /> component that walks new users through Wallet Connection, Asset Selection, the Order Book, and Portfolio Tracking.
• Added hasCompletedTour validation in localStorage so the tour automatically mounts for first-time visitors but skips for returning users who have completed or dismissed it.
• Safely patched src/App.jsx to inject the target CSS classes (.tour-wallet-connect, .tour-asset-selection, etc.) around existing components without breaking layout.

Scope

• Backend API behavior
• Build/CI only
• Docs only
• Frontend / UI

Validation

• npm run build
• npm run lint
  (Note: Verified that localStorage correctly prevents duplicate tour runs).

Links

• Issue(s): Closes Add Interactive User Onboarding Tour #599
• Related PR(s): #

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