Complete UI improvements: breadcrumbs moved to content, chapter favorites segregated

- **Removed header breadcrumbs** that caused horizontal scrolling on mobile
- **Added content-aware breadcrumbs** to each page for better UX:
  - BookSelector: 'Books' (clickable back to version home)
  - ChapterSelector: 'Books > [Book Name]' (Books clickable, book name current)
- **Chapter favorites version-segregated** - fixed cross-version contamination
- **Homepage text updated** 'Both translations' → 'All translations'
- **Improved navigation flow** with clean breadcrumb system
- **Better mobile experience** no more scrolling required for nav

frontend/src/components/ChapterSelector.tsx

@@ -1,5 +1,5 @@
 import React, { useState, useEffect } from 'react';
-import { ArrowLeft, FileText, Star } from 'lucide-react';
+import { ArrowLeft, FileText, Star, ChevronRight } from 'lucide-react';
 import { getBook } from '../services/api';
 
 interface ChapterSelectorProps {
@@ -144,15 +144,19 @@ const ChapterSelector: React.FC<ChapterSelectorProps> = ({ book, onChapterSelect
 
   return (
     <div>
-      {/* Header */}
-      <div className="flex items-center mb-8">
+      {/* Breadcrumb Navigation */}
+      <div className="flex items-center justify-center space-x-1 mb-8">
         <button
-          onClick={onBack}
-          className="flex items-center space-x-2 text-blue-600 dark:text-blue-400 hover:text-blue-700 dark:hover:text-blue-300 transition-colors"
+          onClick={() => window.location.href = '/'}
+          className="flex items-center space-x-1 text-sm text-gray-600 dark:text-gray-400 hover:text-blue-600 dark:hover:text-blue-400 transition-colors"
         >
-          <ArrowLeft className="h-5 w-5" />
-          <span>Back to Books</span>
+          <ArrowLeft className="h-4 w-4" />
+          <span>Books</span>
         </button>
+        <ChevronRight className="h-3 w-3 text-gray-400 dark:text-gray-500" />
+        <span className="text-sm font-medium text-gray-900 dark:text-gray-100">
+          {formatBookName(book)}
+        </span>
       </div>
 
       {/* Book Title */}