fix(dashboard): иконка испытания «Марафонец» (running → footprints)

Иконка Lucide 'running' не существует, поэтому createIcons() оставлял
<i> пустым — у испытания типа 'tests' не было иконки. Заменено на
валидную 'footprints'.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

frontend/dashboard.html

@@ -1961,7 +1961,7 @@
           const pct = c.target > 0 ? Math.min(100, Math.round(c.progress / c.target * 100)) : 0;
           const done = c.completed;
           const claimed = c.claimed;
-          const icon = done ? lci('check-circle', 20) : c.type === 'topic_tests' ? lci('book-open', 20) : c.type === 'high_score' ? lci('target', 20) : c.type === 'perfect' ? lci('diamond', 20) : lci('running', 20);
+          const icon = done ? lci('check-circle', 20) : c.type === 'topic_tests' ? lci('book-open', 20) : c.type === 'high_score' ? lci('target', 20) : c.type === 'perfect' ? lci('diamond', 20) : lci('footprints', 20);
           return `<div class="ch-item${done ? ' done' : ''}${claimed ? ' claimed' : ''}">
             <div class="ch-icon">${icon}</div>
             <div class="ch-body">