Add Azure SQL Bicep templates for hardened and vulnerable configurations

- Introduced `azure-sql-hardened.bicep` demonstrating secure Azure SQL best practices including strong TLS settings, locked-down firewall rules, enforced Transparent Data Encryption, and secure parameter handling.
- Introduced `azure-sql-vulnerable.bicep` showcasing common misconfigurations for educational comparison, including hard-coded credentials, weak TLS settings, and broad firewall access.
- Updated `lesson-05-demo-concise.md` to outline a demo flow for using Copilot to review and harden the vulnerable template, including compliance checks and incident response narratives.
- Created `lesson-05-demos-concise.md` for a structured runbook detailing the demo process, pre-requisites, and key talking points for each segment.

Author: timothywarner