fix: clarify partial object sorting

[anthonymartin]

Pull Request

Description

Fixes the misleading Last Modified sort when ListObjectsV2 returns only the first key-ordered page. The column now identifies that its ordering is limited to loaded objects while a continuation token exists, and users can explicitly load the next page from the header or list footer.

Continuation requests remain bounded to one page. If an appended page fails, the already loaded rows and continuation token are retained, an inline retry action remains available, and the partial-sort disclosure stays visible.

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update
• Code refactoring
• Performance improvement
• Test improvements
• Security fix

Testing

• Unit tests added/updated
• Manual testing completed

pnpm type-check
pnpm lint
pnpm test:run
pnpm prettier --check components/object/list.tsx tests/lib/object-list-source.test.js i18n/locales/*.json
git diff --check

All commands above pass. pnpm format:check remains blocked by the pre-existing formatting issue in components/object/tiff-viewer.tsx; the task-owned files pass Prettier.

Checklist

• Code follows the project's style guidelines
• Self-review completed
• TypeScript types are properly defined
• All commit messages are in English (Conventional Commits)
• All existing tests pass
• No new dependencies added, or they are justified

Related Issues

Closes rustfs/rustfs#6120

Screenshots (if applicable)

N/A — this environment has no authenticated Console/S3 fixture or browser runtime for reliable before/after capture.

Additional Notes

No configuration, storage, API, or migration changes. The UI preserves request scoping and avoids unbounded full-bucket loading.