fix(advisor): accept current Claude usage metadata

[bottlerex]

Summary

• Fix Claude CLI 2.1.251 modelUsage compatibility.
• Preserve fail-closed validation for unknown metadata fields and helper identities.

Changes

• Accept only the observed non-empty metadata strings: canonicalModel, provider, costBasis.
• Permit the observed claude-haiku-4-5-20251001 helper alongside claude-opus-5.
• Add regression coverage and bump plugin version to 0.9.4.

Test Plan

• 26 bridge unit tests passed.
• Live read-only Claude review through the patched bridge succeeded.
• Existing unrelated auth-retry working-tree changes are intentionally excluded from this commit.

NOT_ADVISOR_APPROVED: external Advisor review transport was unavailable during the patch workflow; local tests and live bridge verification are attached as evidence.