Add badges, checkins, and transport endpoints

Introduce gamification and check-in support plus expanded transport/admin APIs. Added DDL for checkins, badges and user_badges. New repositories: badgeRepository, userBadgeRepository, checkinRepository. New routes: admin badge management, admin transport (lines/platforms/stations), public transport endpoints, user checkins and stations endpoints, and user badges on /me. Services updated: adminService (badge CRUD & user assignment), userService (checkins, badge queries), authService (hasAdminRights). Minor package.json name update. These changes implement database, repo, service and route wiring for badges, user_badins and checkin features and additional transport admin routes.

data/ddl/15_user_badges.sql

@@ -0,0 +1,13 @@
+CREATE TABLE IF NOT EXISTS `user_badges` (
+    `id` INT UNSIGNED NOT NULL AUTO_INCREMENT,
+    `userId` UUID NOT NULL,
+    `badgeId` INT UNSIGNED NOT NULL,
+    `unlockedAt` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
+
+    PRIMARY KEY (id),
+    UNIQUE KEY uq_user_badges_user_badge (userId, badgeId),
+    INDEX idx_user_badges_user (userId),
+
+    CONSTRAINT `fk_user_badges_userId` FOREIGN KEY (`userId`) REFERENCES `users` (`id`) ON DELETE CASCADE,
+    CONSTRAINT `fk_user_badges_badgeId` FOREIGN KEY (`badgeId`) REFERENCES `badges` (`id`) ON DELETE CASCADE
+);