feat(compat): adapt local AlphaEvolve evaluators for OpenEvolve

[Yushu-Li]

OpenEvolve evaluators receive a file path, while Google's local AlphaEvolve examples expect a candidate object and return nested scores/insights. Add an explicit, dependency-free adapt_evaluator helper under openevolve.compat so those evaluators can be used unchanged through the existing callable API.

Partially addresses #468: this is the A1 evaluator-contract slice and a local walkthrough. It does not close the issue or provide SDK emulation, config translation, export, or cloud execution.

• Preserve all metrics and insights; require an explicit objective for combined_score. Map configurable failure sentinels/null/non-finite scores to failure metrics without accidentally promoting them above valid negative objectives.
• Add an evaluate-only runner for the upstream circle-packing, TSP and signal-processing examples, with opt-in evolution using the user's OE config. Existing evaluator/config defaults are untouched; no Google dependency is added.

Validation:

• Full python -m unittest discover -s tests -q: 687 tests passed, including 15 new adapter tests and a real controller/worker round-trip with a deterministic provider.
• Black, isort and git diff --check pass.
• Against Google-Cloud-AI/alphaevolve-on-googlecloud at 674dd5e558e917320c251c085e47fae33e1bbcff: all three unchanged seed/evaluator pairs evaluated locally and completed one OE generation through real worker processes using scripted proposals. Original input files remained byte-identical. Network connections were blocked by the validation harness. This verifies interoperability, not learned optimization quality; no paid LLM or real Google service was used.

Limitations are documented: synchronous single-file local evaluators only, no sandbox, and exceptions/timeouts retain OE's existing generic error handling (which can return zero fitness).

AI disclosure: Codex assisted with implementation, tests and documentation for a user-selected existing public issue found during contribution research. All validation reported above was executed locally.

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