feat: Make entire event banner clickable

- Changed banner from div to anchor tag
- Added hover effect (lift + brightness)
- Easier to click for accessibility

templates/index.html

@@ -16,6 +16,15 @@
         box-shadow: var(--shadow-md);
         position: relative;
         overflow: hidden;
+        text-decoration: none;
+        cursor: pointer;
+        transition: var(--transition);
+    }
+
+    .event-banner:hover {
+        transform: translateY(-2px);
+        box-shadow: var(--shadow-lg);
+        filter: brightness(1.05);
     }
 
     .event-banner::before {
@@ -53,31 +62,6 @@
         margin-bottom: var(--spacing-xs);
     }
 
-    .event-banner-title a {
-        color: white;
-        text-decoration: none;
-        display: inline-flex;
-        align-items: center;
-        gap: var(--spacing-xs);
-        transition: var(--transition);
-    }
-
-    .event-banner-title a::after {
-        content: '→';
-        font-size: 0.9em;
-        opacity: 0.7;
-        transition: var(--transition);
-    }
-
-    .event-banner-title a:hover {
-        transform: translateX(4px);
-    }
-
-    .event-banner-title a:hover::after {
-        opacity: 1;
-        transform: translateX(4px);
-    }
-
     .event-banner-meta {
         font-size: var(--font-size-sm);
         opacity: 0.9;
@@ -341,11 +325,11 @@
 
 <!-- Event Banner - Ankieta "Kto weźmie udział?" -->
 {% if next_event %}
-<div class="event-banner">
+<a href="{{ url_for('calendar_event', event_id=next_event.id) }}" class="event-banner">
     <div class="event-banner-icon">📅</div>
     <div class="event-banner-content">
         <div class="event-banner-label">Najbliższe wydarzenie – Kto weźmie udział?</div>
-        <div class="event-banner-title"><a href="{{ url_for('calendar_event', event_id=next_event.id) }}">{{ next_event.title }}</a></div>
+        <div class="event-banner-title">{{ next_event.title }} →</div>
         <div class="event-banner-meta">
             <span>📆 {{ next_event.event_date.strftime('%d.%m.%Y') }} ({{ ['Pon', 'Wt', 'Śr', 'Czw', 'Pt', 'Sob', 'Nd'][next_event.event_date.weekday()] }})</span>
             {% if next_event.time_start %}
@@ -361,16 +345,12 @@
     </div>
     <div class="event-banner-action">
         {% if user_registered %}
-        <a href="{{ url_for('calendar_event', event_id=next_event.id) }}" class="btn-light btn-registered">
-            ✓ Jesteś zapisany/a
-        </a>
+        <span class="btn-light btn-registered">✓ Jesteś zapisany/a</span>
         {% else %}
-        <a href="{{ url_for('calendar_event', event_id=next_event.id) }}" class="btn-light">
-            Zapisz się →
-        </a>
+        <span class="btn-light">Zapisz się →</span>
         {% endif %}
     </div>
-</div>
+</a>
 {% endif %}
 
 <!-- Search Section -->