feat: restructure learning path with new modules and enhanced explanations

- Add CSS Colors, Typography, Advanced Selectors, and Grid modules
- Remove deprecated HTML Marquee module from all languages
- Remove redundant div & span lesson from HTML Block & Inline
- Move SVG module from HTML to CSS section
- Enhance first lessons with comprehensive explanations:
  - Flexbox: historical context, axes concept
  - Colors: named colors, background-color explained
  - Grid: comparison to Flexbox, key properties
- Swap header logo highlight (CRISPIES instead of CODE)
- Use English fallbacks for new modules in non-EN languages
- Fix test to include 'playground' mode

New path: 19 modules (~78 lessons) vs previous 16 modules (62 lessons)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

src/index.html

@@ -20,7 +20,7 @@
 				</button>
 				<a href="#" id="logo-link" class="logo">
 					<img src="./bowl.png" width="40" alt="CODE CRISPIES Logo" />
-					<h1><span class="code-text">CODE</span><span>CRISPIES</span></h1>
+					<h1><span class="code-text">CODE</span><span class="crispies-text">CRISPIES</span></h1>
 				</a>
 				<div class="header-actions">
 					<button id="help-btn" class="help-toggle" data-i18n-aria-label="help" aria-label="Help">?</button>