Run current OATS consumer suites

[zeitlinger]

Summary

• replace the legacy direct OATS invocation with the current CLI config plus root oats.toml
• convert the existing compose and k8s example suites to the current OATS schema
• run them through a gcx wrapper so consumer CI exercises the current OATS path

Why

This gives the current OATS implementation real downstream CI coverage for:

• compose-backed app suites
• k3d / kubernetes-backed app suites
• trace assertions with match_spans
• structured log assertions with regex attribute matching

Validation

• /tmp/oats --config oats.toml --list
• CI will run mise run oats-tests on this branch using the current OATS CLI

[zeitlinger]

This PR switches the consumer suites onto the current OATS CLI, but I am not seeing any GitHub Actions runs for the PR head yet (only EasyCLA). Could a maintainer enable/approve Actions for this fork PR so we can get real consumer CI validation of the compose and k3d cases?

[zeitlinger]

Temporarily closing to retrigger PR workflows on the latest consumer-validation head; reopening immediately.

[zeitlinger]

I reproduced the merge conflict locally and resolved it against current main, but publishing the rebased branch is blocked by GitHub workflow-file permissions: rebasing onto current main pulls in upstream workflow changes, and PAT-based force-push is rejected without workflow scope. If a maintainer can use GitHub's Update branch button or rebase this draft branch from a workflow-write-capable checkout, the current-OATS consumer changes themselves are already resolved locally.