Locked dispute / stake / arbitration constants (ALIP-0005)

Public, machine-readable read of the locked ALIP-0005 dispute constants — parallel to /meta/fees: the stake floor / threshold / percentage / cap (+ the closed-form formula), the triage threshold and arbiter routing, the arbitration fee schedule, the review-hold window, and worked stake examples. Derived from src/policy/dispute-policy.ts, so the values cannot drift from what the substrate enforces; this REST endpoint and MCP policy://disputes serve the identical payload. Unauthenticated; the policy is public (ADR 0009).