feat: complete jobcard client management foundation

config/bootstrap.php

@@ -128,6 +128,16 @@ function can_access_jobcard(int $jobcardId): bool
     return (bool)$stmt->fetchColumn();
 }
 
+function can_access_client(int $clientId): bool
+{
+    $user = current_user();
+    if (!$user) return false;
+    if ($user['role_name'] !== 'Technician') return can('clients.view');
+    $stmt = db()->prepare('SELECT 1 FROM jobcard_assignments ja JOIN jobcards j ON j.id = ja.jobcard_id WHERE ja.user_id = :user AND j.client_id = :client LIMIT 1');
+    $stmt->execute(['user' => $user['id'], 'client' => $clientId]);
+    return (bool)$stmt->fetchColumn();
+}
+
 function audit(string $action, string $entityType, ?int $entityId = null, array $metadata = []): void
 {
     $user = current_user();