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/de/30-html-tables.json

@@ -14,7 +14,7 @@
 			"previewHTML": "",
 			"previewBaseCSS": "body { font-family: system-ui; padding: 20px; background: #f5f5f5; } table { border-collapse: collapse; width: 100%; max-width: 400px; background: white; border-radius: 10px; overflow: hidden; box-shadow: 0 4px 15px rgba(0,0,0,0.1); } caption { padding: 15px; font-weight: 600; font-size: 1.2rem; color: #333; background: #f8f9fa; } th, td { padding: 12px 20px; text-align: left; border-bottom: 1px solid #eee; } th { background: #3498db; color: white; font-weight: 500; } tr:hover { background: #f8f9fa; } tr:last-child td { border-bottom: none; }",
 			"sandboxCSS": "",
-			"initialCode": "<!-- Erstelle eine Tabelle mit caption und Überschriften -->",
+			"initialCode": "",
 			"solution": "<table>\n  <caption>Obstpreise</caption>\n  <tr>\n    <th>Obst</th>\n    <th>Preis</th>\n  </tr>\n  <tr>\n    <td>Apfel</td>\n    <td>1,50 €</td>\n  </tr>\n  <tr>\n    <td>Banane</td>\n    <td>0,75 €</td>\n  </tr>\n</table>",
 			"previewContainer": "preview-area",
 			"validations": [
@@ -48,7 +48,7 @@
 			"previewHTML": "",
 			"previewBaseCSS": "body { font-family: system-ui; padding: 20px; background: linear-gradient(135deg, #667eea 0%, #764ba2 100%); min-height: 100vh; margin: 0; box-sizing: border-box; } table { border-collapse: collapse; width: 100%; max-width: 450px; background: white; border-radius: 12px; overflow: hidden; box-shadow: 0 10px 30px rgba(0,0,0,0.2); } caption { padding: 20px; font-weight: 700; font-size: 1.3rem; color: white; background: transparent; text-shadow: 0 2px 4px rgba(0,0,0,0.2); caption-side: top; } thead { background: linear-gradient(135deg, #667eea 0%, #764ba2 100%); } th { padding: 15px 20px; text-align: left; color: white; font-weight: 500; } tbody tr { border-bottom: 1px solid #eee; } tbody tr:hover { background: #f8f9fa; } td { padding: 15px 20px; color: #333; } tbody tr:last-child { border-bottom: none; }",
 			"sandboxCSS": "",
-			"initialCode": "<!-- Erstelle eine Tabelle mit thead und tbody -->",
+			"initialCode": "",
 			"solution": "<table>\n  <caption>Monatliche Verkäufe</caption>\n  <thead>\n    <tr>\n      <th>Monat</th>\n      <th>Umsatz</th>\n    </tr>\n  </thead>\n  <tbody>\n    <tr>\n      <td>Januar</td>\n      <td>12.500 €</td>\n    </tr>\n    <tr>\n      <td>Februar</td>\n      <td>14.200 €</td>\n    </tr>\n  </tbody>\n</table>",
 			"previewContainer": "preview-area",
 			"validations": [
@@ -87,7 +87,7 @@
 			"previewHTML": "",
 			"previewBaseCSS": "body { font-family: system-ui; padding: 20px; background: #fafafa; } table { border-collapse: collapse; width: 100%; max-width: 400px; background: white; border-radius: 10px; overflow: hidden; box-shadow: 0 4px 15px rgba(0,0,0,0.1); } caption { padding: 15px 20px; font-weight: 600; font-size: 1.1rem; color: #333; text-align: left; background: #f8f9fa; border-bottom: 2px solid #eee; } th, td { padding: 12px 20px; text-align: left; } thead th { background: #2c3e50; color: white; } tbody td { border-bottom: 1px solid #eee; } tbody tr:hover { background: #f8f9fa; } tfoot { background: #ecf0f1; font-weight: 600; } tfoot td { border-top: 2px solid #2c3e50; color: #2c3e50; }",
 			"sandboxCSS": "",
-			"initialCode": "<!-- Erstelle eine vollständige Tabelle mit tfoot -->",
+			"initialCode": "",
 			"solution": "<table>\n  <caption>Bestellübersicht</caption>\n  <thead>\n    <tr>\n      <th>Artikel</th>\n      <th>Preis</th>\n    </tr>\n  </thead>\n  <tbody>\n    <tr>\n      <td>Widget</td>\n      <td>25,00 €</td>\n    </tr>\n    <tr>\n      <td>Gadget</td>\n      <td>35,00 €</td>\n    </tr>\n  </tbody>\n  <tfoot>\n    <tr>\n      <td>Gesamt</td>\n      <td>60,00 €</td>\n    </tr>\n  </tfoot>\n</table>",
 			"previewContainer": "preview-area",
 			"validations": [