fix: remove broken flash-messages include from admin footer; make repertoire columns scrollable

app/public/admin/toast-fragment.php

@@ -0,0 +1,32 @@
+<?php
+/**
+ * Toast fragment endpoint — HTMX target.
+ *
+ * Reads flash messages from the session and returns the toast markup.
+ * Returns an empty 204 when there is nothing to show.
+ * Called via hx-get on the #toast-region aside in the admin footer.
+ */
+require_once __DIR__ . '/../../bootstrap.php';
+require_once __DIR__ . '/../../src/AdminAuth.php';
+
+AdminAuth::requireLogin();
+
+$flash = App::consumeFlash();
+
+if (!$flash['error'] && !$flash['success']) {
+    http_response_code(204);
+    exit;
+}
+?>
+<?php if ($flash['error']): ?>
+<p class="toast toast--error" role="alert">
+    <span class="toast__icon" aria-hidden="true">⚠</span>
+    <?= htmlspecialchars($flash['error']) ?>
+</p>
+<?php endif; ?>
+<?php if ($flash['success']): ?>
+<p class="toast toast--success" role="status">
+    <span class="toast__icon" aria-hidden="true">✓</span>
+    <?= htmlspecialchars($flash['success']) ?>
+</p>
+<?php endif; ?>