Liquidator service: perplex-cli risk subcommand

[ozpool]

Problem

Under-collateralised positions sit on the edge with no path to forced close. The whole risk side of the exchange is missing — losses past collateral cannot be socialised, and there's no incentive payout to keep the system solvent.

Proposal

New subcommand on perplex-cli:

perplex-cli risk --edge-url ... --account 0x... --bearer $JWT

Per block (anvil tick / Sepolia block):

• Pull every open position from the edge (/v1/positions/all — new internal endpoint, gated by an admin JWT claim).
• For each, compute health factor = (collateral + unrealised PnL) / (notional * mmRatioBps / 10000).
• If health < 1, submit a reduce-only IOC market order on behalf of the liquidator wallet, marked liquidation: true.
• On-chain: pay liqBonusBps of notional from the closed position's collateral to the liquidator's address.

Acceptance

• perplex-cli risk runs continuously, logs every health check.
• At least one E2E test: open a position at 20x → push the oracle the wrong way (MockSource) → confirm position is closed automatically and liquidator wallet receives the bonus.
• Metrics on :9101 (or similar) — positions scanned per block, liquidations triggered, bonus paid in USDC.

Notes

This is the biggest remaining production-blocker. Until it ships, a wallet with a busted position can hold a stale entry forever and erode the vault.