Redirect deprecated Production interface to Preview to prevent crashes

[Copilot]

Production interface (docs/index.html) crashes on book selection due to known bugs. Interface is deprecated per project docs but redirect was never implemented.

Changes

Auto-redirect logic (docs/index.html):

// Auto-redirect to Preview interface (Production is deprecated with known bugs)
// Allow ?legacy=1 to bypass redirect for testing
if (!window.location.search.includes('legacy=1')) {
  window.location.replace('./preview/');
}

Documentation update (docs/interfaces.md):

• Clarified legacy bypass parameter (?legacy=1)

Behavior

• / → redirects to /preview/
• /?legacy=1 → loads production interface (testing only)
• Book selection works without crashes in Preview

Screenshots

Preview interface with working book selection:

Preview interface main view:

Original prompt

Production interface is buggy. Either fix or remove. It crashes when I select a book

---

💬 We'd love your input! Share your thoughts on Copilot coding agent in our 2 minute survey.