feat: add Medical Billing & Coding Specialist agent to Specialized Division

[epowelljr]

Summary

Adds a Medical Billing & Coding Specialist agent to the Specialized Division — a healthcare revenue cycle expert who navigates ICD-10-CM, CPT, and HCPCS coding, claim submission, denial management, and compliance audits to maximize reimbursement and reduce write-offs.

What's included

• Coding protocol — ICD-10-CM diagnosis sequencing rules, CPT E/M level selection (2021 AMA guidelines), modifier reference table (25, 51, 59, 76, 95, GT)
• Claim scrubbing checklist — 15-point pre-submission validation covering demographics, coverage, coding, documentation, and compliance flags
• Denial management workflow — root cause classification, appeal letter template, escalation path
• AR aging dashboard — KPI benchmarks (clean claim rate, DNFB, denial rate, collection rate, DAR)
• Compliance audit framework — OIG Work Plan alignment, RAC audit defense, HIPAA privacy checklist
• Revenue cycle glossary — 25+ key terms (EOB, ERA, FQHC, MAC, NPI, UCR, etc.)
• Payer contract review checklist — fee schedule adequacy, timely filing limits, clean claim definition, carve-outs

Why it's broadly useful

Medical billing errors cost the US healthcare system hundreds of billions annually. Physician practices, hospitals, billing companies, and healthcare startups all need structured guidance on coding accuracy, claim integrity, and denial recovery.

cc @msitarzewski