FX.74 Suggestions and roadmap items link both ways in /admin

Staff can now link a /suggest ask to the roadmap item that builds it, from either page: /admin/suggestions shows each suggestion's linked items (key, title, release) with Unlink and a Link to roadmap box (item key like FX.26, release:key, or #id); the item's edit page has a Suggestions panel (linked asks with status and votes, Link a suggestion by number, Unlink). Staff only; linking tells nobody. RoadmapSuggestions + migration 125 (roadmap_item_suggestions, nothing deleted).

Checked 2026-11-06 in code: link, duplicate refusal, both-way reads and unlink against the live database. Pages linted; not yet viewed in a browser.