feat: admin server assignment in user management

backend/db.js

@@ -80,6 +80,7 @@ async function initSchema(connection) {
     active TINYINT(1) NOT NULL DEFAULT 0,
     email_verified TINYINT(1) NOT NULL DEFAULT 0,
     source ENUM('netease','skin') NOT NULL DEFAULT 'netease',
+    admin_servers JSON,
     verify_token VARCHAR(255),
     verify_expires DATETIME,
     reset_token VARCHAR(255),
@@ -264,6 +265,7 @@ async function migrateAdditions(db) {
   try { await db.execute("ALTER TABLE tickets MODIFY type ENUM('report','suggestion','appeal','result_appeal') NOT NULL"); } catch {}
   try { await db.execute("ALTER TABLE tickets MODIFY status ENUM('pending','processing','awaiting_info','appealing','resolved','rejected','closed') NOT NULL"); } catch {}
   try { await db.execute("ALTER TABLE users ADD COLUMN source ENUM('netease','skin') NOT NULL DEFAULT 'netease'"); } catch {}
+  try { await db.execute("ALTER TABLE users ADD COLUMN admin_servers JSON"); } catch {}
 
   try { await db.execute(`CREATE TABLE IF NOT EXISTS polls (id INT AUTO_INCREMENT PRIMARY KEY, title VARCHAR(200) NOT NULL, description TEXT, options JSON NOT NULL, group_name VARCHAR(100) NOT NULL DEFAULT '', server_name VARCHAR(100) NOT NULL DEFAULT '', start_time DATETIME, end_time DATETIME, active TINYINT(1) NOT NULL DEFAULT 1, created_by INT, created_at DATETIME DEFAULT CURRENT_TIMESTAMP, INDEX idx_active (active), INDEX idx_group_server (group_name, server_name)) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4`); } catch {}
   try { await db.execute(`CREATE TABLE IF NOT EXISTS poll_votes (id INT AUTO_INCREMENT PRIMARY KEY, poll_id INT NOT NULL, user_id INT NOT NULL, option_index INT NOT NULL, created_at DATETIME DEFAULT CURRENT_TIMESTAMP, UNIQUE KEY uk_poll_user (poll_id, user_id), INDEX idx_poll (poll_id)) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4`); } catch {}