fix(storybook): correct staticDirs path for storybook images

[AlephLau]

Summary

The staticDirs configuration in .storybook/main.ts was incorrectly mapping public/img to bundles/pimcorestudioui/img/storybook.

Since the storybook images are located in public/img/storybook/, this caused all SVG documentation images to return 404 errors when running Storybook locally.

Changes

• Fixed the staticDirs path from public/img to public/img/storybook

How to test

1. Run npm install in the assets/ directory
2. Run npm run storybook
3. Navigate to the Guidelines page in Storybook
4. Verify that SVG images (Design-principles.svg, layout-widgets.svg, etc.) now load correctly

[github-actions]

CLA Assistant Lite bot:
Thank you for your submission, we really appreciate it. Like many open-source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution. You can sign the CLA by just posting a Pull Request Comment same as the below format.

---

I have read the CLA Document and I hereby sign the CLA

---

_{You can retrigger this bot by commenting recheck in this Pull Request}

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud