Implement Secure Data Access with Aembit and Tool Use

Elaborate on the `CRMAccessTool` by integrating Aembit for secure, policy-based access to a simulated CRM system. The tool should enforce granular permissions, ensuring the `SalesGuidanceAgent` can only retrieve data relevant to its current context and authorized by Aembit. Show how the agent would dynamically call this tool based on a sales query requiring customer-specific information. Detail the Aembit policy structure that would govern this access. Also, incorporate Libretto for routing requests to Llama 4 Maverick, ensuring optimal model selection and performance.