v2026.5.29-zmb.1 — split-token accessors

Fork release atop upstream nullclaw/nullclaw v2026.5.29 (commit b25c6eb), carrying one commit: cumulative prompt/completion token-split accumulation plus promptTokensUsed()/completionTokensUsed() accessors beside tokensUsed().

Consumed by usezombie to bill platform-model token spend by side. Drop this fork and return the pin to the upstream tag once upstream exposes equivalent split accessors.

Patch reviewed in #1. Suite parity: pristine v2026.5.29 and this release fail only the same 5 pre-existing redis-environment integration tests.