fix: js and css vite preloading broken

[tomek2k1]

• Resolves: First attempt to choose team avatar from Nextcloud Files fails with error #2757

Summary

Due to the partial renaming, the CSS and JS preloading broke.
The appName is "teams", but the app's ID is "circles". As a result, window.OC.filePath() generates the wrong path to the JS and CSS files during preloading.
By resetting the appName in vite.config.ts and setting the assetsPrefix, the change is minimal and has no side effects.

TODO

Checklist

• [x]Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)
• Labels added where applicable (ex: bug/enhancement, 3. to review, feature component)
• Milestone added for target branch/version (ex: 32.x for stable32)

AI (if applicable)

• The content of this PR was partly or fully generated using AI

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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