Initial commit: YesChef family shopping list and recipe app

Backend (.NET 10 minimal API):
- Vertical slice architecture with feature folders
- Postgres via EF Core with initial migration
- JWT auth with family invite code registration
- REST endpoints for stores, shopping lists, items, recipes
- SignalR hub for real-time list collaboration (per-list groups
  and lists-overview group for live list creation/archival/progress)
- Multi-stage Dockerfile

Frontend (SvelteKit + Svelte 5 runes, Tailwind v4):
- Mobile-first PWA with web manifest and service worker
- Bottom-nav layout, login/register, lists overview, list detail,
  stores management, recipes (list/create/detail with add-to-list)
- SignalR client with reference-counted connection
- Real-time updates on both lists overview and list detail pages

Infrastructure:
- docker-compose.yml with postgres, backend, frontend services
  and Traefik labels for path-based routing (/api, /hubs to backend)
- .env.example with required config

End-to-end tests (Playwright):
- test-e2e.mjs: single-user flow (auth, stores, lists, items, recipes)
- test-e2e-multiuser.mjs: two-user real-time sync coverage

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.gitignore

@@ -0,0 +1,23 @@
+## .NET
+bin/
+obj/
+*.user
+*.suo
+*.cache
+
+## Node
+node_modules/
+build/
+.svelte-kit/
+
+## Environment
+.env
+
+## IDE
+.vs/
+.vscode/
+.idea/
+
+## OS
+Thumbs.db
+.DS_Store