refactor: Convert project from JavaScript to TypeScript

- Converted all .js files to .ts
- Added TypeScript configuration (tsconfig.json)
- Added ESLint and Prettier configuration
- Updated package.json dependencies
- Modified Docker and application configurations

tests/startup.test.ts

@@ -0,0 +1,13 @@
+const { spawnSync } = require('child_process');
+
+describe('Bot Startup', () => {
+  test('exits with code 1 if DISCORD_TOKEN is missing', () => {
+    // Clear DISCORD_TOKEN
+    const env = { ...process.env };
+    delete env.DISCORD_TOKEN;
+
+    const result = spawnSync('node', ['src/index.js'], { env, encoding: 'utf-8' });
+    expect(result.status).toBe(1);
+    expect(result.stderr || result.stdout).toMatch(/DISCORD_TOKEN is missing/);
+  });
+});