feat(website): [WIP] add Reference Comparison to sequence details

[theosanderson-agent]

Adds an optional Reference comparison tab to sequence details and the search-results sequence modal, using gensplore@0.0.14. Selecting the tab compares the entry with its configured reference and marks substitutions, deletions, insertions, and ambiguous bases. Switching tabs unloads the component; existing sequence downloads and text displays remain available.

The component consumes LAPIS’s existing alignment and separate insertion calls, preserving supplied gap placement. Terminal Ns are excluded from alignment but remain visible as coverage-gap labels and faded letters on nucleotide and amino-acid tracks; internal ambiguity also remains visible. Gensplore supports up to 256 alignment edits for amino-acid comparison. Segmented entries have a segment selector, and entries with multiple references use their assigned reference. The tab is hidden for revoked entries, entries without consensus sequences, and segments without an available reference.

A same-origin /seq/[accessionVersion]/reference-comparison route loads the component on demand inside a 550px-high iframe. Gensplore 0.0.17 reduces the gap between nucleotide callouts and amino-acid ribbons. The route checks the public entry before loading its data. Reference annotations are fetched server-side from NCBI using the configured public INSDC reference accession, cached, and accepted only when the sequence exactly matches the configured reference. No submitted sequence is sent to NCBI. Without matching annotations, the comparison uses the configured nucleotide reference and displays a notice.

The feature’s component directory, types, props, data helpers, route, page title, iframe labels, errors, and tests consistently use Reference Comparison terminology.

Validation: all 873 website tests pass, including tab loading, segment switching, reference selection, insertion filtering, preserved internal gaps, and annotation fallback. Type checks and formatting pass.

Test deployment: https://feat-gensplore-sequence-p.loculus.org

🚀 Preview: https://feat-gensplore-sequence-p.loculus.org