Gap closure: feedback loops, traceability, and new /content-audit skill

- NEW /content-audit skill: GDD-specified content vs implemented content gap
  report with COMPLETE/IN PROGRESS/EARLY/NOT STARTED per system
- balance-check: Fix & Verify Cycle phase (fix → re-verify → propagate-design-change)
- perf-profile: Scope & Timeline Decision phase for M/L effort optimizations
- playtest-report: Action Routing phase categorizes findings → design/balance/bugs/polish
- review-all-gdds: Phase 4 Cross-System Scenario Walkthrough (multi-system sequences)
- story-done: Test-Criterion Traceability (each AC mapped to a test, BLOCKING if >50% untested)
- code-review: ADR Compliance Check (ARCHITECTURAL VIOLATION / ADR DRIFT / MINOR DEVIATION)
- setup-engine: upgrade subcommand (pre-upgrade API scan, migration plan, VERSION.md update)
- story-readiness: Asset References Check (verifies referenced asset paths exist)
- validate-assets.sh: invalid JSON now exits 1 (blocking); naming issues exit 0 (warning)
- workflow-catalog.yaml + sprint-plan: /scope-check wired into production phase

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.claude/docs/workflow-catalog.yaml

@@ -221,6 +221,16 @@ phases:
         repeatable: true
         description: "Verify all acceptance criteria, check GDD/ADR deviations, close the story"
 
+      - id: scope-check
+        name: "Scope Check"
+        command: /scope-check
+        required: false
+        repeatable: true
+        artifact:
+          glob: "production/sprints/sprint-*.md"
+          note: "Run when stories are added mid-sprint, or before sprint retrospectives"
+        description: "Detect scope creep by comparing current sprint scope to original epic scope. Run (a) when stories are added mid-sprint, or (b) before sprint retrospectives."
+
       - id: sprint-status
         name: "Sprint Status"
         command: /sprint-status