test(framework): Harden local k8s harness evidence

[msheller]

Summary

• add reviewer-facing local k8s evidence artifacts for the F7 harness
• map seeded run, TaskExecutor Pod, and per-task Secret evidence without leaking Secret payloads
• require the new artifacts in the verifier and document how reviewers should inspect them

Stack

• Stacked on feat(framework): Add real k3d launch path harness #7401
• Base branch: codex/f7-integrated-k3d-real-launch-path

Validation

• python -m py_compile framework/dev/k8s/common.py framework/dev/k8s/harness.py framework/dev/k8s/real_launch.py framework/dev/k8s/observations.py framework/dev/k8s/verify_evidence.py framework/py/flwr/supercore/superexec/executor/kubernetes_executor_harness_test.py
• python -m pytest framework/py/flwr/supercore/superexec/executor/kubernetes_executor_harness_test.py
• python -m ruff check framework/dev/k8s/real_launch.py framework/dev/k8s/verify_evidence.py framework/py/flwr/supercore/superexec/executor/kubernetes_executor_harness_test.py
• git diff --check
• framework/dev/k8s/test-real-launch-path.sh --skip-build --output-dir /private/tmp/f7d0-secret-redaction-real-smoke
• rg -n "task-token|dGFzay10b2tlbg==" /private/tmp/f7d0-secret-redaction-real-smoke returned no matches