style(dashboard): fix bunched buttons in card headers

This commit adds a proper flexbox layout to the '.card-actions' CSS class. Previously, action buttons (like Export and Refresh on the Analytics page) were bunching up because they lacked a flex container with appropriate gap and wrapping rules. It also updates the '.card-header' to wrap gracefully on smaller screens.

static/js/dashboard.js

@@ -284,7 +284,7 @@ class Dashboard {
                         <h3 class="card-title">Model Registry</h3>
                         <p class="card-subtitle">Manage model availability and custom pricing</p>
                     </div>
-                    <div class="card-actions" style="display: flex; gap: 0.5rem; align-items: center; flex-wrap: wrap;">
+                    <div class="card-actions">
                         <select id="model-provider-filter" class="form-control" style="margin-bottom: 0; padding: 4px 8px; width: auto;">
                             <option value="">All Providers</option>
                             <option value="openai">OpenAI</option>