feat(backend): bootstrap express app with error handling

packages/backend/package.json

@@ -0,0 +1,39 @@
+{
+  "name": "@flashcard/backend",
+  "version": "0.1.0",
+  "private": true,
+  "type": "module",
+  "main": "dist/index.js",
+  "scripts": {
+    "dev": "tsx watch src/index.ts",
+    "build": "tsc -p tsconfig.json",
+    "start": "node dist/index.js",
+    "typecheck": "tsc --noEmit",
+    "test": "vitest run",
+    "test:watch": "vitest",
+    "db:generate": "drizzle-kit generate",
+    "db:migrate": "tsx src/db/migrate.ts",
+    "db:seed": "tsx src/db/seed.ts"
+  },
+  "dependencies": {
+    "@flashcard/shared": "*",
+    "better-sqlite3": "^11.0.0",
+    "drizzle-orm": "^0.33.0",
+    "express": "^4.19.0",
+    "multer": "^1.4.5-lts.1",
+    "xlsx": "^0.18.5",
+    "zod": "^3.23.0"
+  },
+  "devDependencies": {
+    "@types/better-sqlite3": "^7.6.0",
+    "@types/express": "^4.17.0",
+    "@types/multer": "^1.4.0",
+    "@types/node": "^20.0.0",
+    "@types/supertest": "^6.0.0",
+    "drizzle-kit": "^0.24.0",
+    "supertest": "^7.0.0",
+    "tsx": "^4.16.0",
+    "typescript": "^5.5.0",
+    "vitest": "^2.0.0"
+  }
+}