cf46b27610
P0-1 (limits.go): Allow()方法改为全程使用写锁保护counters map读写，避免RLock写入时的data race P0-2 (ticket_workflow.go+ticket_handler.go): Assign/Resolve/Close操作先查询ticket存在性和状态，返回明确的CS_TICKET_4001/CS_TKT_4002/CS_TICKET_4092/CS_TICKET_4093错误码，handler根据错误前缀路由HTTP状态码 P1-1 (ticket_store.go): 移除GetStats中3处手动rows.Close()，只保留defer Close()