BLAST Results — UX batch

Motivation

Continuation of the UI/UX pass on the BLAST Results page. Two gaps remained after confirming the table sort indicators and empty states already exist: results couldn't be shared as a link to the exact view, and the result Files table rendered in API order with no way to sort.

Verified-already-present (left untouched): Descriptions table sort indicators (SortableHeader in BlastHitsTable), zero-hit empty states (DescriptionsTabBody, NoResultFilesPanel), and Alignments incremental windowing. Deferred (need streaming/virtualization or visual tuning): per-file download progress bar (#24), Descriptions virtualization (#29), per-tab scroll restore (#21), wide-table scroll-shadow cue (#25), taxonomy expand/collapse-all (#26), and keyboard row navigation (#30).

User-facing change

• #28 Copy link — the result header action row gains a Copy link button that copies the current view URL (including the active ?tab=), so a specific result tab can be shared and reopened exactly.
• #27 Sortable Files table — the Files tab table headers (File / Size / Modified) are now clickable to sort, with a chevron direction indicator and aria-sort. Default stays API order until a header is clicked; name sorts ascending, size / modified default to largest / newest first.

Code change summary

• web/src/pages/blastResults/BlastJobHeader.tsx: handleCopyLink (copies window.location.href) + a Link2 "Copy link" button next to "Copy citation".
• web/src/pages/blastResults/BlastResultsTable.tsx: ResultsFileTable now holds sortBy / sortDir state and a useMemo sort; ResultsHeaderCell renders a sortable button with ChevronUp/ ChevronDown indicators and aria-sort.

Validation evidence

• cd web && npm run build → clean.
• cd web && npm test -- --run blastResults BlastResults → 145 passed (including the existing BlastJobHeader.test.ts).
• npx eslint on both changed files → clean.

No backend / API / IaC changes.