Evaluate a local embedding router on semantic routing challenges #55

Extend the offline routing experiment with semantic paraphrases and near-miss cases, then compare Lucid current deterministic routing with a small local embedding candidate.

Scope:

• Keep this experiment-only; no runtime integration.
• Add family-isolated semantic and negative challenge cases.
• Support an optional local Ollama embedding adapter.
• Record accuracy, high-confidence wrong direct actions, abstention/clarification behavior, and latency.
• Test installed local embedding models without committing model files or generated reports.

Adoption rule: a local model must improve meaningful semantic coverage without introducing unsafe confident actions or unacceptable latency. If the deterministic router remains sufficient, record that result and do not add runtime complexity.