service entitlement persists as a floor, not a pinned value

Agent-decided, under AGENTS.md §6, and deliberately weaker than the episode pinning one round below. The service inequality uses only inf_t w_t(c) > 0, so requiring a pinned entitlement would forbid legitimate reprioritisation for nothing. What is forbidden is driving the floor to zero. The fixture that settles it shrinks a share geometrically: never zero, never defeated, never transferred, and on any finite prefix it satisfies the finite proxy for the service condition while the mechanism guaranteeing it is already gone.