feat(spec-phase): prohibition probe — surface "must-NOT" constraints (#644) (#1149)

Adds the spec-time prohibition probe (spec-phase Step 5.6) — the second adapter of the probe-core resolution model. Surfaces unwritten must-NOT constraints as negative SPEC acceptance criteria with test/judgment verification tiers; fail-closed at verify time. Per ADR-550. Closes #644.

docs/INVENTORY.md

@@ -304,6 +304,7 @@ Full roster at `gsd-core/references/*.md`. References are shared knowledge docum
 | `continuation-format.md` | Session continuation/resume format. |
 | `domain-probes.md` | Domain-specific probing questions for discuss-phase. |
 | `edge-probe.md` | Spec-phase edge-completeness probe — 8-category edge taxonomy, shape classification, and the `requirements → checks → verifier` resolution model (Step 5.5). |
+| `prohibition-probe.md` | Spec-phase prohibition-completeness probe — the two-stage adversarial-recall → precision protocol that surfaces the unwritten *must-NOT* constraints (values/safety/ethics), with status×verification (`test`/`judgment`) tiering and canon-referral breadcrumbs (Step 5.6); second adapter of the `probe-core` resolution model. |
 | `gate-prompts.md` | Gate/checkpoint prompt templates. |
 | `loop-hook-dispatch.md` | Generic dispatch contract for consuming `gsd_run loop render-hooks <point> --raw` output in any host-loop workflow — envelope shape, per-kind dispatch rules (contribution/step/gate), and liveness banner. |
 | `scout-codebase.md` | Phase-type→codebase-map selection table for discuss-phase scout step (extracted via #2551). |