feat(altyapı): yerel MongoDB, Axum backend ve Vite frontend iskeleti

- docker-compose.dev.yml: MongoDB 7, tek düğümlü replica set (port 27020)
- Backend: Axum + tokio, GET /api/health
- Frontend: React + TypeScript + Vite, /api proxy, geçici durum ekranı
- Kök package.json: npm run dev ile DB + backend + frontend
- backend/api.http örnek istekler

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

backend/Cargo.toml

@@ -0,0 +1,12 @@
+[package]
+name = "kakeibo"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+axum = "0.8.9"
+dotenvy = "0.15.7"
+serde_json = "1.0.154"
+tokio = { version = "1.54.1", features = ["full"] }
+tracing = "0.1.44"
+tracing-subscriber = { version = "0.3.23", features = ["env-filter"] }