feat: schema v1.7 + sections/shifts frontend

- Universeel festival/event model (parent_event_id, event_type)
- event_person_activations pivot tabel
- Event model: parent/children relaties + helper scopes
- DevSeeder: festival structuur met sub-events
- Sections & Shifts frontend (twee-kolom layout)
- BACKLOG.md aangemaakt met 22 gedocumenteerde wensen

apps/app/package.json

@@ -90,6 +90,7 @@
     "@typescript-eslint/parser": "7.18.0",
     "@vitejs/plugin-vue": "6.0.1",
     "@vitejs/plugin-vue-jsx": "5.1.1",
+    "baseline-browser-mapping": "^2.10.16",
     "eslint": "8.57.1",
     "eslint-config-airbnb-base": "15.0.0",
     "eslint-import-resolver-typescript": "3.10.1",