Add BFS (banking & financial services) coverage matrix (docs/coverage/bfs.md)

[kmadan]

Goal

Add `docs/coverage/bfs.md` mapping every policy under `industry_specific/bfs/v1/` to its source obligation. Follow the format of docs/coverage/eu-ai-act.md.

Why this matters

Model risk management and fair lending are among GOPAL's highest enterprise-value use cases. The repo currently ships only 2 policies in `industry_specific/bfs/v1/` (model risk, fair lending). A coverage matrix:

1. Makes the existing coverage discoverable
2. Names the obvious gaps as contribution targets
3. Pairs with the MAS FEAT framework issue (#21) and the upcoming lending-model example (#26) to make BFS GOPAL's most complete vertical.

What to cite

Each row should cite the relevant US, EU, or APAC banking supervisor's guidance:

• US: SR 11-7 (Fed/OCC Model Risk Management), Regulation B (ECOA, 12 CFR 1002), Regulation Z, CFPB UDAAP guidance, OCC Heightened Standards
• EU: EBA Guidelines on internal governance, ECB Guide to internal models (TRIM), EU AI Act high-risk credit-decisioning provisions
• APAC: MAS FEAT principles, HKMA AI in banking guidance, MAS TRM Guidelines

Likely structure

Group by obligation type, not by file:

• Model risk — governance, validation, monitoring, documentation
• Fair lending — disparate impact, ECOA adverse-action, protected-class evaluation
• Explainability — adverse-action codes, customer-facing reason codes
• Consumer protection — UDAAP, customer-suitability AI checks

Acceptance criteria

• Matrix lists every BFS policy file and marks Implemented / Scaffold / Planned
• Each row cites the source regulator and document
• docs/coverage/README.md links to the new matrix
• At least 3 "📋 Planned" rows identify real gaps to seed follow-up PRs
• Cross-references to issues #21 (MAS FEAT) and #26 (lending-model example)

Get help

This is mostly a reading task — no Rego required. Banking compliance, model risk, or fair-lending background welcome but not required.