Add rigorous route promotion evidence

[alan-d-smith]

Summary

• add manifest-locked paired route comparison with uncertainty and fail-closed evidence gates
• record consumed v1 and independently authored/reviewed sealed v2 holdouts
• document source-bound Kimi/MiniMax evidence and the rejected logic/local-model experiments

Verification

• 569 passed, 1 Windows symlink skip
• Ruff check and format clean
• strict mypy clean across 72 source files
• Python 3.10 syntax compile clean in WSL
• both measurement manifests verify

Runtime impact

No scored routing or container behavior changes. The existing public image remains the current evidence-backed baseline; the new sealed holdout is reserved for the consequential exact Gemma/Kimi comparison.