Scaffold project and implement config, DB schema/queries

- Set up package.json (ESM, scripts), tsconfig.json, vitest.config.ts
- Install runtime and dev dependencies
- Add CLAUDE.md with architecture notes and code quality rules
- Config module with env var parsing and JWT_SECRET validation
- DB schema: users + files tables with FK cascade
- DB queries: createUser, getUserBy*, createFile, getFileById, getFilesByUserId, deleteFile
- Tests for config, db/users, db/files (15 tests passing)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tsconfig.json

@@ -0,0 +1,19 @@
+{
+  "compilerOptions": {
+    "target": "ES2022",
+    "module": "NodeNext",
+    "moduleResolution": "NodeNext",
+    "outDir": "dist",
+    "rootDir": "src",
+    "strict": true,
+    "esModuleInterop": true,
+    "skipLibCheck": true,
+    "forceConsistentCasingInFileNames": true,
+    "resolveJsonModule": true,
+    "declaration": true,
+    "declarationMap": true,
+    "sourceMap": true
+  },
+  "include": ["src/**/*"],
+  "exclude": ["node_modules", "dist", "tests"]
+}