feat: project scaffolding and env config loader

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

package.json

@@ -0,0 +1,31 @@
+{
+  "name": "file-converter",
+  "version": "0.1.0",
+  "private": true,
+  "type": "module",
+  "scripts": {
+    "start": "node src/app.js",
+    "worker": "node src/worker.js",
+    "cleanup": "node src/cleanup.js",
+    "test": "vitest run"
+  },
+  "dependencies": {
+    "docx": "^9.7.1",
+    "dotenv": "^17.4.2",
+    "express": "^5.2.1",
+    "express-rate-limit": "^8.6.1",
+    "file-type": "^22.0.1",
+    "mammoth": "^1.12.0",
+    "mariadb": "^3.5.3",
+    "multer": "^2.2.0",
+    "pdf-lib": "^1.17.1",
+    "pdfjs-dist": "^6.2.108",
+    "puppeteer": "^25.4.0",
+    "sharp": "^0.35.3",
+    "uuid": "^14.0.1"
+  },
+  "devDependencies": {
+    "supertest": "^7.2.2",
+    "vitest": "^4.1.10"
+  }
+}