fix(server): set `cache-control` header only after processing image

[ucw]

🔗 Linked issue

❓ Type of change

• [ ] 📖 Documentation (updates to the documentation, readme, or JSdoc annotations)
• [x] 🐞 Bug fix (a non-breaking change that fixes an issue)
• [ ] 👌 Enhancement (improving an existing functionality like performance)
• [ ] ✨ New feature (a non-breaking change that adds functionality)
• [ ] 🧹 Chore (updates to the build process or auxiliary tools and libraries)
• [ ] ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

Currently, the Cache-Control header is set before image processing takes place. This can lead to the caching of a 500 error in Cloudflare if an exception occurs during image processing. The changes in this pull request move the setting of the Cache-Control header after the image processing to prevent the caching of 500 errors in such scenarios.

📝 Checklist

• [ ] I have linked an issue or discussion.
• [ ] I have updated the documentation accordingly.

[codecov[bot]]

Codecov Report

Attention: 9 lines in your changes are missing coverage. Please review.

Comparison is base (fc8a0de) 54.10% compared to head (873ecfa) 54.10%. Report is 4 commits behind head on main.

Files	Patch %	Lines
src/server.ts	0.00%	9 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #200 +/- ## ======================================= Coverage 54.10% 54.10% ======================================= Files 11 11 Lines 1083 1083 Branches 45 45 ======================================= Hits 586 586 Misses 497 497 ```

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