Add endpoints specific to DiscountConditions

Editor assessment

A compact, correctly formed feature header. The medusa scope matches the monorepo convention, the subject is imperative and specific about what was added — dedicated endpoints for DiscountConditions rather than general-purpose changes — which keeps the changelog entry meaningful. It sits comfortably within length limits and carries the PR number for traceability. The absence of a body is the only missed opportunity: noting which HTTP methods and routes were introduced, and whether the endpoints are admin-only, would help API consumers assess adoption cost without reading the diff. No breaking markers appear and none are warranted for additive endpoints, so a minor version inference for the core package is appropriate. Spec-compliant and readable; merely under-documented for an API-surface change.