fix(mesh): abbreviation-safe sentence splitting in EvidenceExtractor (#2170)

[mrveiss]

Summary

• Adds negative lookbehinds for Dr., Mr., Mrs., Ms., St., vs., e.g., i.e., U.S.
• Prevents false sentence splits on common abbreviations
• 4 new tests (16 total for EvidenceExtractor)

Closes #2170

[github-actions]

✅ SSOT Configuration Compliance: Passing

🎉 No hardcoded values detected that have SSOT config equivalents!