fix: update legacy runtime path

- Changed the legacy runtime path from 'legacy-runtime.js' to 'index.js'
in runtime configuration.
- Added a new start script (start.js) to check for the existence of the
built TypeScript server entrypoint and import it.

server/index.js

@@ -1,11 +1,13 @@
 #!/usr/bin/env node
+// Load environment variables before other imports execute
+import './load-env.js';
 import fs from 'fs';
 import path from 'path';
 import { fileURLToPath } from 'url';
+import { dirname } from 'path';
 
 const __filename = fileURLToPath(import.meta.url);
-const __dirname = path.dirname(__filename);
-const distEntrypoint = path.join(__dirname, 'dist', 'bootstrap.js');
+const __dirname = dirname(__filename);
 
 const installMode = fs.existsSync(path.join(__dirname, '..', '.git')) ? 'git' : 'npm';