Topics page fixes

[marcellamaki]

Summary

• Updates 'search' button to be 'filter' button per spec (and to reduce confusion about multiple references to 'search'ing)
• Fixes tab behavior - tabs update main view and routes, whereas filter button opens filtering side panel
• Folder tab doesn't display when we are at the last child folder
• replaces breadcrumbs that seem to have disappeared on mobile

References

Fixes #8847

Figma spec for medium screens (where the toggling changes were most relevant)

Implementation

Reviewer guidance

• Any oversights or regressions that I missed?

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Testing checklist

• Contributor has fully tested the PR manually
• If there are any front-end changes, before/after screenshots are included
• Critical user journeys are covered by Gherkin stories
• Critical and brittle code paths are covered by unit tests

PR process

• PR has the correct target branch and milestone
• PR has 'needs review' or 'work-in-progress' label
• If PR is ready for review, a reviewer has been added. (Don't use 'Assignees')
• If this is an important user-facing change, PR or related issue has a 'changelog' label
• If this includes an internal dependency change, a link to the diff is provided

Reviewer checklist

• Automated test coverage is satisfactory
• PR is fully functional
• PR has been tested for accessibility regressions
• External dependency files were updated if necessary (yarn and pip)
• Documentation is updated
• Contributor is in AUTHORS.md

[rtibbles]

There are still some issues here from testing.

[rtibbles]

When first navigating to the topics page, the folder header is not highlighted, because it requires the query parameter to be set.

Overall, I think the interaction on mobile is still confusing - the header links being used as buttons to toggle the side panels feels counterintuitive. As such, the fact that the button for filter is only available in tablet layout but not smaller layouts seems like an issue.

[rtibbles]

Also, when first navigating to the search tab, I think we should show the search side panel - otherwise we are requiring users to click the search header and then open the search panel separately, making two clicks to express what they want to do.

[marcellamaki]

Updated interactions -- this briefly broke my brain, but I think it covers the scenarios discussed earlier...

[rtibbles]

Manual testing checks out - just need to prevent the redundant navigation error.