chore: bump next (#7046)

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## Summary by CodeRabbit

* **Chores**
* Updated Next.js dependency from v15.3.1 to v15.3.8 across 13+ example
projects and website packages, including starter projects, experimental
features, and test applications.
* Re-enabled the automated code fixes functionality in continuous
integration workflow. The autofix commit step is now active with
standardized double-quoted commit message formatting to maintain
consistency across commits.

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settings.</sub>

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Author: KATT

package.json

@@ -39,7 +39,7 @@
     "@trpc/react-query": "npm:@trpc/react-query",
     "@trpc/server": "npm:@trpc/server",
     "clsx": "^2.0.0",
-    "next": "^15.3.1",
+    "next": "^15.3.8",
     "react": "^19.1.0",
     "react-dom": "^19.1.0",
     "superjson": "^1.12.4",