feat(skills): add product-expert roadmap-audit + spec-review strategist

A standalone, self-triggering skill that acts as Relicario's product
strategist: audits the roadmap and reviews freshly-brainstormed release
specs for product/market fit, emitting PM-ready relay directive blocks.
Advisory only — the user stays the decision-maker.

- Two modes: roadmap audit (default) and spec review (verdict:
  PROCEED / RESCOPE / CUT / PIVOT).
- Four-lens engine run as parallel subagents: ground-truth (verify
  claims vs code/git, distinguishing an in-flight lift from real drift),
  jobs-to-be-done, market/competitive, and strategy synthesis.
- Fast by default; `deep` adds live competitive web research.
- Durable by design: lenses read living docs (README/ROADMAP/STATUS/
  CHANGELOG/specs) at runtime, so new surfaces/segments/features are
  picked up automatically. The one static asset, competitive-landscape.md,
  carries a last-reviewed date + freshness protocol.
- Wires a post-brainstorm product gate into CLAUDE.md's Planning section.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VQbgrP6KQW5pibjbPEoTSs

CLAUDE.md

@@ -90,6 +90,8 @@ Source code: `ssh://git@git.adlee.work:2222/alee/relicario.git`
 
 **Before starting any planning or implementation task**, search `docs/superpowers/specs/` for a spec covering the feature area, and `docs/superpowers/plans/` for any existing implementation plan. The specs are the authoritative design record; plans track per-milestone implementation details. Once a plan exists, execute it via the release workflow (see **Release lifecycle** below) — not directly via subagent-driven-development or executing-plans unless the workflow is unavailable.
 
+**Product gate.** After brainstorming a new release spec — before handing it to writing-plans — run `/product-expert review <spec-path>` for a product/market-fit gut-check (PROCEED / RESCOPE / CUT / PIVOT). The `product-expert` skill also runs standalone (`/product-expert`) any time you want to audit the whole roadmap and get PM-ready directives for modifications or pivots; add `deep` for live competitive web research. It only advises — you stay the decision-maker.
+
 Core references (read before touching crypto, data model, or architecture):
 - `docs/superpowers/specs/2026-04-11-relicario-design.md` — threat model, entropy analysis, crypto pipeline, crate layout
 - `docs/superpowers/specs/2026-04-18-relicario-typed-items-design.md` — typed-item data model and envelope