Implement the 003-remove-combatant feature that adds the possibility to remove a combatant from an encounter

specs/003-remove-combatant/quickstart.md

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+# Quickstart: Remove Combatant
+
+**Feature**: 003-remove-combatant
+
+## Prerequisites
+
+- Node.js 18+, pnpm
+- Repository cloned, `pnpm install` run
+
+## Development
+
+```bash
+git checkout 003-remove-combatant
+pnpm test:watch                    # Run tests in watch mode during development
+pnpm --filter web dev              # Dev server at localhost:5173
+```
+
+## Verification
+
+```bash
+pnpm check                         # Must pass before commit (format + lint + typecheck + test)
+```
+
+## Implementation Order
+
+1. **Domain**: Add `CombatantRemoved` event type → implement `removeCombatant` pure function → tests
+2. **Application**: Add `removeCombatantUseCase` → re-export
+3. **Web**: Add `removeCombatant` to `useEncounter` hook → add remove button in `App.tsx`
+
+## Key Files
+
+| Layer | File | Purpose |
+|-------|------|---------|
+| Domain | `packages/domain/src/remove-combatant.ts` | Pure removal function |
+| Domain | `packages/domain/src/events.ts` | CombatantRemoved event type |
+| Domain | `packages/domain/src/__tests__/remove-combatant.test.ts` | Acceptance tests |
+| Application | `packages/application/src/remove-combatant-use-case.ts` | Use case orchestration |
+| Web | `apps/web/src/hooks/use-encounter.ts` | Hook integration |
+| Web | `apps/web/src/App.tsx` | UI remove button |