Azure SQL Developer: integration tests with Testcontainers

Write integration tests that start a real Azure SQL Developer (Private Preview) engine from code, provision appdb, run the test against it, and tear the container down. This is the Azure SQL engine, not the SQL Server image.

This skill is about tests that manage their own engine lifecycle in-process (Testcontainers). It is DISTINCT from azuresql-db-ci, which wires the same engine into a CI pipeline as a service container via workflow YAML. If the goal is a CI job rather than in-code test setup, use azuresql-db-ci instead.

Use the right image (interception point)