Parse employee skills CSV files, identify skill categories and individual skills, look up employee IDs from an employees table, and generate idempotent SQL INSERT statements for skill_categories, skills, and employee_skills tables.

解析员工技能CSV文件，识别技能类别和具体技能，从员工表中查找员工ID，并为技能类别表、技能表和员工技能表生成幂等的SQL INSERT语句