test(provider): integration-test the type x provider matrix in a local KSail cluster

[devantler]

🤖 Generated by the Agentic Engineer

Child of #33. Follows each driver child; the matrix grows as they land.

User story

As a contributor, I want each provider combination exercised in a local KSail cluster so that a driver that provisions but never becomes queryable fails in CI rather than in production.

Acceptance criteria

• Integration coverage runs in a local KSail environment and exercises the type × provider matrix that is implemented at the time.
• Each case asserts the behaviour, not just that resources were created: the store accepts a write and returns it through the product's published output contract. A green provisioning step with no query is not sufficient evidence.
• The default-off state is covered too — with the flag off, no engine resources are created.
• Runtime and cost are bounded so this stays runnable in CI; if the full matrix is too heavy, the split between what runs per-PR and what runs on a schedule is explicit.
• Failures identify which provider combination broke without needing a local reproduction.

Note

This repository already has flake history in its sandboxed integration tests (#22, ~8% of CI runs). Whatever is added here should not repeat that pattern — prefer explicit readiness waits over sleeps.

Rough size: M, growing with the matrix.