method-rules-gate-contracts-bplisted

# Gate BP contract (normative satellite of `method-rules-gate-contracts`) Split out of the main contract in v1.7.0 for the same reason maintenance-rules lives outside the default bundle (method-rules §10): this is ~2,300 words that **gates F, C, V1, V2, V3, R1, R2, P and LOCK never need**, and gate-check loads the contract at every gate. The main file keeps BP's one-line row so the gate list stays complete; everything else about BP lives here. **Load this skill when**: you are running the `stage-6-blueprint` skill, the `amend-blueprint` skill, or a gate check whose gate is `BP`. Otherwise do not. ## Gate BP (stage 6 — implementation blueprint, post-LOCK, pre-build) BP is the only gate that runs **after** LOCK. Its state deliberately does not live in the cycle's `gates` object — that subtree froze when the cycle locked — but in the root-level `state.blueprint.gate` block (state-schema), the same placement reasoning as `maintenance`. Everything else about gate discipline is unchanged: three layers, gatekeeper, manifest pin, `gate-verdict` journal row, audit-trail section, founder approval. - **Entry** (one sentence, identical in stage 6, gate-check, and here): `gates.LOCK` is `passed` — OR `gates.LOCK` is `failed` AND a complete `mvp-pack/` exists on disk AND `unvalidated-build-decision.md` + its `will-override` journal row exist. A UBD recorded against any earlier gate is an explicit **stop**: there is no pack to refine — stage 6 needs the pack's core loop, DoD an