New Search "Include taxonomy columns" toggle

Motivation

Issue #29 item #4. The New Search Output-format control is an integer dropdown (form.outfmt: number) and cannot express a field-level specifier, so a researcher who wanted the subject taxid / scientific name columns had to hand-write additional_options with the exact -outfmt 7 std staxids sscinames string and know the YAML-quoting hazard. The multi-token outfmt runtime is now verified end-to-end live (elb-openapi 4.22; see the finalizer rebuild note), so the UI can expose it safely.

User-facing change

• The Algorithm Parameters section now has an "Include taxonomy columns (taxid + scientific name)" checkbox under Output format.
• When checked:
• It forces the Output format to 7 — Tabular + comments (and disables the dropdown, since the format is now fixed) so the visible format matches the emitted specifier.
• The submit emits the verified canonical UNQUOTED specifier -outfmt 7 std staxids sscinames via additional_options. std leads so the qseqid column stays first (the shard merge groups by qseqid).
• The integer outfmt field is omitted from the request so the options string carries exactly one -outfmt flag — a double flag would make the shard merge's parser read only the leading code and drop the staxids / sscinames columns.
• A user-supplied -outfmt in additional_options still wins (the helper de-dupes on the flag), so power users keep full control.
• Works with sharding: the merged result keeps the extended # Fields: header (taxid + scientific name reach the dashboard Scientific Name column / Taxonomy tab). Requires a database that ships taxonomy data (e.g. core_nt).

API / IaC diff summary

• web/src/pages/blastSubmitModel.ts — new outfmt_taxonomy_columns: boolean form field (default false).
• web/src/pages/blastSubmit/AlgorithmParametersSection.tsx — the toggle checkbox; disables the Output-format dropdown when on.
• web/src/pages/blastSubmit/useSubmitMutation.ts — buildEffectiveAdditionalOptions appends -outfmt 7 std staxids sscinames when the toggle is on; the submit request sends outfmt: undefined in that case.
• No backend behaviour change — the internal submit already accepts the multi-token specifier via additional_options and omits -outfmt when the outfmt field is absent. No IaC change.

Validation evidence

• cd web && npm test -- --run src/pages/blastSubmit/taxonomyOutfmt.test.ts — 3 passed (off → no -outfmt; on → canonical unquoted specifier; user -outfmt not doubled).
• cd web && npm test -- --run src/pages/blastSubmit/ — 203 passed.
• cd web && npm run build — clean.
• uv run pytest -q api/tests/test_blast_config_sharding.py — 49 passed (new test_taxonomy_columns_path_omits_integer_outfmt_field: omitted integer outfmt + multi-token additional_options → exactly one -outfmt, sharding gate engages).
• The emitted -outfmt 7 std staxids sscinames wire format is the same one verified live end-to-end on elb-cluster-01 (merged # Fields: header carried subject tax ids / subject sci names, taxid 562 / Escherichia coli).