feat: add reproducible Galaxy workflow link to the Pangenome section header

Follow-up to #1342 (organism-page Pangenome section).

## Background

The Pangenome section header currently renders only the title + a `bundleId · version` chip. The #1342 acceptance criteria / Figma also call for a link to the **reproducible Galaxy workflow** used to build the pangenome (the "ⓘ More" affordance in the mock). This was **deferred** during #1342 because the workflow URL wasn't available to wire up yet (per @NoopDog), and Copilot flagged the omission on the PR.

During #1342 code review, the `Pangenome.workflowUrl` field was **removed** from the type and mock `pangenomes.json` (it was unused). This ticket re-introduces it and renders the link once the URL is available.

## Scope

- Re-add `workflowUrl` to the `Pangenome` type (`app/apis/catalog/brc-analytics-catalog/common/pangenome.ts`) and populate it in `catalog/output/pangenomes.json` (and, ultimately, the real `pangenomes.json` build — #1341).
- Render the reproducible-workflow link / "More" action in the Pangenome section header (`app/views/OrganismView/components/Main/components/PangenomeSection/pangenomeSection.tsx`), matching the Figma.
- Confirm the exact URL source with @NoopDog before wiring.

## Acceptance

- [ ] Pangenome section header links to the reproducible Galaxy workflow.
- [ ] `workflowUrl` sourced from `pangenomes.json` (not hardcoded).
- [ ] Gated behind the `pangenome` flag like the rest of the section; `tsc`/lint/build green.