fix: remove placeholder comments and improve German translations

- Remove placeholder comments from initialCode fields
- Fix typo: "wichtig Wort" -> "wichtigen Wort" in de/20-html-elements.json
- Improve German validation messages for readability
- Use consistent terminology (Eingabefeld instead of Input)

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

lessons/29-html-figure.json

@@ -14,7 +14,7 @@
 			"previewHTML": "",
 			"previewBaseCSS": "body { font-family: system-ui; padding: 20px; background: #f5f5f5; } figure { margin: 0; background: white; border-radius: 12px; overflow: hidden; box-shadow: 0 4px 15px rgba(0,0,0,0.1); max-width: 400px; } figure img { width: 100%; height: 200px; object-fit: cover; display: block; background: linear-gradient(135deg, #667eea 0%, #764ba2 100%); } figcaption { padding: 15px 20px; color: #555; font-size: 0.95rem; border-top: 1px solid #eee; }",
 			"sandboxCSS": "",
-			"initialCode": "<!-- Create a figure with an image and caption -->",
+			"initialCode": "",
 			"solution": "<figure>\n  <img src=\"https://picsum.photos/400/200\" alt=\"A beautiful landscape\">\n  <figcaption>A beautiful mountain landscape at sunset.</figcaption>\n</figure>",
 			"previewContainer": "preview-area",
 			"validations": [
@@ -43,7 +43,7 @@
 			"previewHTML": "",
 			"previewBaseCSS": "body { font-family: system-ui; padding: 20px; background: #1e1e1e; } figure { margin: 0; background: #2d2d2d; border-radius: 10px; overflow: hidden; max-width: 500px; } pre { margin: 0; padding: 20px; overflow-x: auto; } code { color: #9cdcfe; font-family: 'Fira Code', 'Consolas', monospace; font-size: 14px; line-height: 1.5; } figcaption { padding: 12px 20px; color: #888; font-size: 0.85rem; background: #252525; border-top: 1px solid #3d3d3d; }",
 			"sandboxCSS": "",
-			"initialCode": "<!-- Create a figure with a code snippet -->",
+			"initialCode": "",
 			"solution": "<figure>\n  <pre><code>function greet(name) {\n  return `Hello, ${name}!`;\n}</code></pre>\n  <figcaption>A simple greeting function in JavaScript</figcaption>\n</figure>",
 			"previewContainer": "preview-area",
 			"validations": [
@@ -77,7 +77,7 @@
 			"previewHTML": "",
 			"previewBaseCSS": "body { font-family: system-ui; padding: 20px; background: linear-gradient(135deg, #ffecd2 0%, #fcb69f 100%); min-height: 100vh; margin: 0; box-sizing: border-box; } figure { margin: 0; background: white; border-radius: 15px; overflow: hidden; box-shadow: 0 10px 30px rgba(0,0,0,0.15); max-width: 500px; padding: 15px; display: grid; grid-template-columns: repeat(2, 1fr); gap: 10px; } figure img { width: 100%; height: 120px; object-fit: cover; border-radius: 8px; background: linear-gradient(45deg, #ff6b6b, #feca57); } figcaption { grid-column: 1 / -1; padding: 10px 5px 5px; color: #666; font-size: 0.9rem; text-align: center; }",
 			"sandboxCSS": "",
-			"initialCode": "<!-- Create a gallery with multiple images -->",
+			"initialCode": "",
 			"solution": "<figure>\n  <img src=\"https://picsum.photos/200/120?1\" alt=\"Photo 1\">\n  <img src=\"https://picsum.photos/200/120?2\" alt=\"Photo 2\">\n  <img src=\"https://picsum.photos/200/120?3\" alt=\"Photo 3\">\n  <img src=\"https://picsum.photos/200/120?4\" alt=\"Photo 4\">\n  <figcaption>My vacation photo gallery</figcaption>\n</figure>",
 			"previewContainer": "preview-area",
 			"validations": [