feat(approaches): Fill coverage gaps (14 uncovered use cases)

[Meyanis95]

Context

14 of 20 use cases have no corresponding approach. v0.3.0 requires every use case to have at least one.

Current coverage (6 use cases covered)

• private-bonds → approach-private-bonds
• private-derivatives → approach-private-derivatives
• private-identity → approach-private-identity
• private-money-market-funds → approach-private-money-market-funds
• private-stablecoins → approach-private-payments
• private-rwa-tokenization → approach-private-trade-settlement (partial)

Note: approach-private-payments links to private-stablecoins, not private-payments — the broader payments use case is uncovered.

Extend existing approaches

Use case becomes a variant, linked explicitly:

Use case	Extend which approach	Rationale
private-payments	approach-private-payments	Approach currently links to stablecoins only; broaden to cover general payment rails
private-corporate-bonds	approach-private-bonds	Same asset class, different issuer type
private-government-debt	approach-private-bonds	Same asset class, sovereign issuer
private-stocks	approach-private-bonds or approach-private-trade-settlement	Equity tokenization follows similar settlement patterns
private-commodities	approach-private-trade-settlement	Commodity settlement is a trade-settlement variant
private-fx	approach-private-trade-settlement	FX swaps are a trade-settlement variant
private-repo	approach-private-trade-settlement	Repurchase agreements are collateralized trade settlement
private-treasuries	approach-private-payments	Treasury management is payment orchestration

Need new approaches (~5)

Use case	Why it needs its own approach
private-messaging	Fundamentally different primitive (communication, not settlement)
private-oracles	Data delivery, not asset transfer — different trust model
private-read	Private RPC / data access — infrastructure-level privacy
private-registry	Registry privacy (identity, ownership) — different from transaction privacy
private-supply-chain + private-procurement	Supply chain traceability with selective disclosure — could share one approach

Scope

• For extensions: add the use case as an explicit variant in the existing approach, with pattern differences called out
• For new approaches: write from scratch following template, including context-aware I2I/I2U recommendations (chore(approaches): Add I2U analysis to existing approaches #124) and persona POVs (feat(approaches): Deepen persona POVs #137) from the start

Done when

All 20 use cases link to at least one approach (via the "Recommended Approaches" section in each use case).