refactor(infra): directory structure (#4615)

packages/backend/server/src/app.controller.ts

@@ -0,0 +1,13 @@
+import { Controller, Get } from '@nestjs/common';
+
+@Controller('/')
+export class AppController {
+  @Get()
+  info() {
+    const version = AFFiNE.version;
+    return {
+      compatibility: version,
+      message: `AFFiNE ${version} Server`,
+    };
+  }
+}