Replace the loyalty program config (fidélité, paliers)
Upserts the ENTIRE loyalty plan — this is a full replace, not a patch, so send every field including the complete tier ladder (at least one rung; omitted rungs are deleted). GET the current config first and edit that document. The change takes effect immediately for every subsequent accrual, redemption and tier resolution, and it does NOT restate existing ledger entries, so past earns keep the rate they were granted at. 400 on a malformed plan (e.g. an empty tiers array).
Authorizations
Authorization: Bearer <token>. Accepts EITHER a Keycloak access token (scopes-in-token) OR an opaque POS session token; both resolve to the same pos.* scope vocabulary the route guards enforce.

