feat: add first-time onboarding tour for Stellar flow

[Dami24-hub]

This PR implements Issue #17: First-time user onboarding tour for Stellar flow. It introduces a lightweight, interactive, and fully accessible onboarding wizard to guide new users through the Stellar stealth payment flow, reducing immediate bounce rates and clarifying the platform's core UX mechanics.

A new Git branch feature/stellar-onboarding-tour was created and pushed to remote upstream prior to development.

Problem Context

First-time visitors landing on the demo are often overwhelmed by the specialized stealth-address terminology, the wallet connection mechanics, and the overall UI. Without a clear step-by-step introduction, users struggle to build a proper mental model of how private Stellar payments function, leading to drop-offs.

Proposed Changes

Tour Implementation & Architecture

• Library Selection: Integrated driver.js due to its ultra-lightweight footprint (<10 KB gzipped) and stellar accessibility compliance.
• State Persistence: Implemented a check on localStorage.wraith.tourCompleted. The tour automatically triggers for new users on the home/send page and sets this flag to true upon completion or manual dismissal, preventing annoying auto-relaunches.
• Manual Reset: Added a "Take the tour" interactive link within the site footer to let users manually restart the flow at any time.

The 5-Step Guided Flow

All copy has been externalized to src/i18n/en.json to preserve future localization capabilities:

1. Step 1 (Header/Wallet): Introduces Wraith as a private payment layer on Stellar testnet and prompts a wallet connection.
2. Step 2 (Post-Connect): Explains the cryptographic safety of the local stealth-key derivation message.
3. Step 3 (Recipient Input): Guides users on entering a Stellar stealth meta-address or a .wraith domain name.
4. Step 4 (Amount Input): Explains how fresh stealth addresses are generated dynamically on-chain.
5. Step 5 (Submit/Send): Explains the privacy mechanism (unlinkable target addresses) seen by network observers.

Accessibility & UX Guardrails

• Keyboard Navigation: Enabled full keyboard traversal (Arrow keys to navigate, Esc to instantly dismiss).
• Reduced Motion: Hooked into the prefers-reduced-motion media query to disable animations gracefully for users with motion sensitivities.
• Non-Blocking Overlay: Configured the overlay to ensure it does not trap user clicks, allowing seamless abandonment or manual UI exploration.

---

Technical Checklist

• Lightweight onboarding library added (<10KB gzipped impact).
• All 5 steps mapped to correct UI anchor elements.
• State tracking via localStorage fully functional.
• Hardcoded strings avoided; copy centralized in src/i18n/en.json.
• Manual trigger added to the application footer.

---

Types of Changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

---

Testing & Verification

Automated Tests

• Added a comprehensive Playwright E2E test suite in tests/onboarding.spec.ts covering:
  • The happy-path workflow completion (Steps 1 through 5).
  • Dismissal via the Skip button and the Esc key.
  • Verification that localStorage correctly persists and blocks auto-firing upon page reload.

Manual Verification Checklist

• Persistence: Verified that refreshing the page after closing the tour does not re-trigger it.
• Footer Link: Confirmed clicking "Take the tour" in the footer forces a manual restart regardless of storage flags.
• A11y: Focus management manually tested using Chrome DevTools and keyboard-only tracking.

Closes #17

[vercel]

@Dami24-hub is attempting to deploy a commit to the truthixify's projects Team on Vercel.

A member of the Team first needs to authorize it.

[drips-wave]

@Dami24-hub Great news! 🎉 Based on an automated assessment of this PR, the linked Wave issue(s) no longer count against your application limits.

You can now already apply to more issues while waiting for a review of this PR. Keep up the great work! 🚀

Learn more about application limits

[truthixify]

Closing as duplicate. Issue #17 is being handled in #39 which was opened first (waiting on a rebase).

If #39's content doesn't end up covering everything you have here (i18n strings, specific tour steps, custom mock approach), feel free to open a small follow-up PR after #39 lands. Otherwise, open Stellar Wave issues: https://github.com/wraith-protocol/demo/issues?q=is%3Aopen+label%3A%22Stellar+Wave%22

Thanks @Dami24-hub.