feat(engine): persistenza enigmi, inventario strutturato, HP mostri

Fase 2 del remediation plan:
- set_puzzle_state / is_puzzle_solved per enigmi area
- update_inventory su character_items con add/remove/equip/list
- combat() legge HP da combat_state e persiste danno
- dm_cycle inietta campaign_id nei tool che ne hanno bisogno
- helpers db: dedup inventario, remove/equip per nome

Fase 4 del remediation plan:
- test integrazione dm_cycle con LLM mockato (5 test)
- test WebSocket handler con mock (4 test)
- CI minimo .gitea/workflows/test.yml

.gitea/workflows/test.yml

@@ -0,0 +1,22 @@
+name: test
+on: [push, pull_request]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Setup Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3.13"
+      - name: Install dependencies
+        run: |
+          python3 -m pip install --upgrade pip
+          pip install pytest pytest-asyncio httpx
+      - name: Run tests
+        run: |
+          PYTHONPATH=$(pwd)/src python3 -m pytest tests/ -v
+      - name: Verify DB init
+        run: |
+          PYTHONPATH=$(pwd)/src python3 -c "from src.engine import db; db.init_db()"