Function classify_liquidity_gap 

pub fn classify_liquidity_gap(
    obligation: &PmSettlementObligation,
    facts: &PmAccountSettlementFacts,
    pool: &PmSettlementPoolSnapshot,
    config: &PmSettlementPoolConfig,
) -> Result<PmLiquidityClassification, PmSettlementModelError>

Classify a settlement liquidity gap without mutating runtime state.

Stale facts return Unavailable; zero or fully liquid-covered obligations return Paid; otherwise a PM-healthy account can receive a timing bridge only when recoverable collateral, pool cash, and post-bridge utilization all satisfy policy. Policy violations classify as SettlementDebt.