[Security] Harden devConsoleAssetsMiddleware against path traversal

[gonzaloriestra]

Why is this change necessary?

This PR hardens the devConsoleAssetsMiddleware to prevent path traversal vulnerabilities when serving dev console assets.

How to test your changes?

CI

Post-release steps

None.

• I have bug-tested this on a real app (desktop)
• I have bug-tested this on a real app (mobile, if applicable)
• I have added a focused regression test
• I have added an integration test
• I have added a unit test

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PR created automatically by Jules for task 14434859044729996754 started by @gonzaloriestra

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