feat(design-verification): add scope-critique pass (#238)

[uta2000]

Summary

• Adds ### Step 4.5: Scope critique step to skills/design-verification/SKILL.md with a 5-question strategic-shape pass (scope, dependencies, simpler alternatives, observability, config surface)
• New skills/design-verification/references/scope-critique.md with expanded prompt text, per-question red-flag lists, and bias-resistance checklist
• Wires the pass into Step 4 Consolidation via a call-out that explicitly owns BLOCKER-row promotion into the Step 5 ### Blockers list (labelled [Scope critique Q<N>]), and excludes assumptions-only mode
• Adds scope-independence Note to Verification Depth so the pass is governed alongside Category 25
• Pure markdown — zero JS, zero config schema changes, zero hook changes

Motivated by #236 post-creation review: 6 strategic issues bypassed existing brainstorming + design-verification + self-review gates. The new pass fills that gap.

Test Plan

• AC-1 grep -c "^### Step 4.5: Scope critique" skills/design-verification/SKILL.md → 1
• AC-2 grep -c "Should this exist\|Could it ship smaller\|simpler version\|Observability\|Config surface" skills/design-verification/SKILL.md → 5
• AC-3 skills/design-verification/references/scope-critique.md exists with expanded prompt text
• AC-4 Existing SKILL.md anchor count unchanged at 11 (no regression in Step 1-7 / Verification Depth / Quality Rules / Additional Resources headings)
• AC-5 Manual sanity run against advisor: tiered stuck mode + soft checkpoints + settings hint #236 pre-correction design surfaced 6 of 6 strategic issues (≥3 required)

Code Review Summary

Initial review: pr-review-toolkit:code-reviewer → APPROVED, no blocking issues.

Dogfood + senior-developer panel (opus, 3 personas) surfaced 4 findings, all fixed in this PR:

Severity	Persona	Rule	Fix
important	Staff Eng	leaky-boundary	Step 4 call-out now explicitly owns BLOCKER-row promotion into Step 5 ### Blockers (labelled [Scope critique Q<N>])
important	Staff Eng	wrong-abstraction	Section relocated from ## Scope critique (H2 outside Process) to ### Step 4.5: Scope critique (H3 inside Process); scope-independence Note added to Verification Depth
important	Product Eng	scope-creep	assumptions-only mode now explicitly excluded from the Scope critique pass — matches narrow-mode contract
minor	Staff Eng	missing-seam	Q2 now prefers exploration_results.schema/pipeline/ui evidence first; opens referenced files directly only when the dependency domain is not covered

The scope-critique pass was run against its own design (dogfooding) and produced 2 genuine WARNINGs (Q3 — reference file size trade-off; Q4 — AC-5 is LLM-self-assessed, acknowledged trade-off). Both are noted trade-offs rather than blockers. The pass did NOT surface the assumptions-only scope-creep issue — a blind spot caught by the senior panel's Product Engineer lens.

Implementation Context

Design Decisions

• Fast-track lifecycle — issue design-verification: add scope-critique pass #238 serves as the design; no separate brainstorming or design doc generated
• Section placed as ### Step 4.5: Scope critique inside ## Process (between Step 4 and Step 5) so Verification Depth governs it alongside every other check
• Reference file holds the bias-resistance checklist and per-question red flags; keeping them out of SKILL.md prevents bloat
• BLOCKER promotion into the top-level Blockers list is owned by the Step 4 Consolidation call-out (single authority), not the Step 4.5 description (which only describes the findings-table output)
• assumptions-only mode skips the pass — assumption verification is a deliberately narrow mode and strategic critique is out of scope for it

Verification Results

No blockers found during codebase exploration. Senior-panel judgment findings from the review process (4 total) all fixed in this revision.

Key Patterns Used

• H3 ### Step N: numbered steps inside the ## Process H2 (existing pattern; Step 4.5 inserted between 4 and 5)
• Scope-independent capabilities noted after the Verification Depth table (parallel to Category 25)
• Reference files live in skills/<skill-name>/references/
• Output-format fenced block uses prescriptive severity table (PASS / WARNING / BLOCKER)

Closes #238