Add regression tests for lock poison-recovery paths and Whitaker CI/Makefile wiring

[coderabbitai]

Summary

Edge-harvest, recipe, MST, and invariant changes have strong tests, but the new poison-recovery paths (PoisonError::into_inner usages) and the CI/Makefile Whitaker lint wiring lack direct regression coverage.

Required changes

• Add focused unit tests that deliberately poison the touched mutexes/locks (e.g. DistanceCache, chutoro-test-support/src/lib.rs::RecordingLayer, chutoro-core/src/session/clock.rs::FixedMonotonicClock, chutoro-cli/src/logging.rs::init_logging) and assert recovery behaviour.
• Add contract tests (or CI smoke checks) for the new lint-clippy/lint-whitaker Makefile targets, the whitaker-installer install/cache steps in .github/workflows/ci.yml, and the dataset_recipe_phase_order nextest timeout overrides in .config/nextest.toml.

Affected areas

• chutoro-core/src/hnsw/distance_cache.rs
• chutoro-core/src/session/clock.rs
• chutoro-cli/src/logging.rs
• chutoro-test-support/src/lib.rs
• Makefile, .github/workflows/ci.yml, .config/nextest.toml

Acceptance criteria

• New tests exercise poisoned-lock recovery for each touched mutex and pass.
• CI/Makefile lint wiring has an automated check (e.g. a CI job step or script) verifying the targets/steps run as expected.

References

• PR: $pr_url
• Requested by: @$assignee

[coderabbitai]

🔗 Related PRs

#122 - CPU session scaffold: SessionConfig, ClusteringSession, build_session [closed]
#128 - Implement session append edge harvesting (11.1.3) [closed]
leynos/dear-diary#28 - Add Whitaker to lint checks [closed]
#129 - Prove SIMD tail padding and dispatch selection (2.2.7) [closed]
#130 - Refresh repository documentation guidance [merged]

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