Add Docker Compose deployment

- Dockerfile: Node.js 20 Alpine, single-stage build
- docker-compose.yml: backend + nginx, named volume for SQLite
- server.js: updated for Docker (env vars for PORT/DATA_DIR)
- nginx.conf: updated for Docker networking (backend hostname)
- README.md: full deployment instructions

deploy/package.json

@@ -0,0 +1,14 @@
+{
+  "name": "project-tracker-backend",
+  "version": "1.0.0",
+  "description": "Project Tracker API",
+  "main": "server.js",
+  "scripts": {
+    "start": "node server.js"
+  },
+  "dependencies": {
+    "better-sqlite3": "^11.0.0",
+    "cors": "^2.8.5",
+    "express": "^4.18.2"
+  }
+}