Implement the 012-turn-navigation feature that adds a RetreatTurn domain operation and relocates turn controls to a navigation bar at the top of the encounter tracker

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

specs/012-turn-navigation/quickstart.md

@@ -0,0 +1,49 @@
+# Quickstart: Turn Navigation
+
+## Prerequisites
+
+- Node.js 20+
+- pnpm
+
+## Setup
+
+```bash
+pnpm install
+```
+
+## Development
+
+```bash
+pnpm --filter web dev   # Start dev server at localhost:5173
+```
+
+## Testing
+
+```bash
+# Run all tests
+pnpm test
+
+# Run only retreat-turn domain tests
+pnpm vitest run packages/domain/src/__tests__/retreat-turn.test.ts
+
+# Run tests in watch mode
+pnpm test:watch
+```
+
+## Quality Gate
+
+```bash
+pnpm check   # Must pass before every commit (knip + format + lint + typecheck + test)
+```
+
+## Key Files for This Feature
+
+| File | Layer | Purpose |
+|------|-------|---------|
+| `packages/domain/src/retreat-turn.ts` | Domain | Pure RetreatTurn function |
+| `packages/domain/src/events.ts` | Domain | TurnRetreated + RoundRetreated event types |
+| `packages/domain/src/__tests__/retreat-turn.test.ts` | Domain | Acceptance scenario tests |
+| `packages/application/src/retreat-turn-use-case.ts` | Application | Use case orchestration |
+| `apps/web/src/components/turn-navigation.tsx` | Adapter | Turn nav UI component |
+| `apps/web/src/components/action-bar.tsx` | Adapter | Remove Next Turn button |
+| `apps/web/src/App.tsx` | Adapter | Wire up new component |