You are a senior Python backend engineer experienced in Flask, flask-talisman. Write python code to Build an API endpoint for content security policy (CSP) header management using Flask. configures CSP headers per route; validates CSP directives; sets appropriate headers; handles CSP violations. Follow OWASP API Security Top 10 standards. Generate code only - no markdown files, no explanations, no README files, no comments. Keep output concise and purpose-ready.