fix flaky typecheck test (#1072)

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<!-- This is an auto-generated comment: release notes by coderabbit.ai
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## Summary by CodeRabbit

* **Chores**
* Updated TypeScript build configuration to exclude development build
artifacts (Next.js dev output) so compilation skips generated dev files,
improving build/IDE performance for backend and dashboard projects.

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apps/backend/tsconfig.json

@@ -42,6 +42,7 @@
     ".next/dev/types/**/*.ts"
   ],
   "exclude": [
-    "node_modules"
+    "node_modules",
+    ".next/dev"
   ]
 }

apps/dashboard/tsconfig.json

@@ -42,6 +42,7 @@
     ".next/dev/types/**/*.ts"
   ],
   "exclude": [
-    "node_modules"
+    "node_modules",
+    ".next/dev"
   ]
 }