feat: add OpenAPI documentation and comprehensive test suite

- Add OpenAPI schema endpoint at /openapi.json with proper logging
- Make server exportable for testing by wrapping app.listen in module check
- Add Jest test suite covering all API endpoints
- Improve request logging with IP addresses and timestamps
- Add development dependencies for testing (jest, supertest)

test/openapi.test.js

@@ -0,0 +1,23 @@
+const request = require('supertest');
+const fs = require('fs');
+
+describe('OpenAPI Schema Endpoint', () => {
+  let app;
+
+  beforeAll(() => {
+    // Import the app after modifications
+    app = require('../index.js');
+  });
+
+  test('should serve OpenAPI schema at /openapi.json', async () => {
+    // Read the expected schema from the file
+    const expectedSchema = JSON.parse(fs.readFileSync('./openapi.json', 'utf-8'));
+    
+    const response = await request(app)
+      .get('/openapi.json')
+      .expect(200)
+      .expect('Content-Type', /application\/json/);
+      
+    expect(response.body).toEqual(expectedSchema);
+  });
+});