fix: update entrypoint in d2.config.js to point to TypeScript file

- Change entrypoint from './src/index' to './src/index.tsx'
- Resolves build failure: 'Could not resolve entrypoint ./src/index'
- Build system now correctly finds the converted TypeScript entry file

Co-Authored-By: [email protected] <[email protected]>

Author: devin-ai-integration[bot]

d2.config.js

@@ -8,7 +8,7 @@ const config = {
     coreApp: true,
 
     entryPoints: {
-        app: './src/index',
+        app: './src/index.tsx',
     },
 };