feat(website): add Required Segments filter for multi-segmented viruses

[anna-parker]

resolves #5840

Add a new SegmentFilter component to the search form that lets users easily filter for sequence entries that include specific segments of multi-segmented viruses.

Previously, users had to manually set the length filter to > 0 for each segment they wanted to require, which was unintuitive and created a cluttered UI. The new "Required segments" section appears at the top of the Sequence Filters panel (only for multi-segmented organisms) and shows a checkbox per segment. Checking a segment automatically sets length_{segment}From = 1, filtering to entries where that segment is present. Unchecking it clears the constraint.

The filter is rendered only when the underlying length_{segment}From fields exist in the metadata schema, making it a no-op for organisms that haven't configured per-segment length fields.

Screenshot

PR Checklist

• All necessary documentation has been adapted.
• The implemented feature is covered by appropriate, automated tests.
• Any manual testing that has been done is documented (i.e. what exactly was tested?)

🚀 Preview: https://feat-segment-presence-fil.loculus.org

[claude]

This PR may be related to: #5840 (Create a Segment presence filter checkbox for multi-segmented viruses and remove or decrease the size length check boxes)

[claude]

Claude finished @anna-parker's task in 2m 46s —— View job

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Code Review

• Gather context
• Read changed files
• Analyze code quality, security, performance, testing, documentation
• Post inline comments
• Final review summary

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The implementation is clean and well-structured. The component correctly guards against non-multi-segmented organisms, uses DisabledUntilHydrated per the project conventions, and gracefully no-ops when length_${segment}From fields aren't in the schema.

Two things worth addressing:

No tests – the PR checklist acknowledges this. Even a single integration test that checks a segment presence checkbox and verifies the URL param / search result count changes would give good confidence.

Hardcoded field name convention – length_${segmentName}From is assembled inline in two places (lines 32 and 45). If this naming convention ever changes, it'll need updating in multiple places. A small constant or utility would make this more robust.

The two inline comments cover a performance nit (memoising ungroupedMetadataFilters()) and the more significant interaction between the new checkbox and an existing per-segment length filter.

[anna-parker]

bulk revise 2 seqs with files errored on both integration tests, Ive been seeing this fail a lot so I assume its just flake

[theosanderson]

@codex review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Keep them coming!

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[theosanderson]

nice