This merge restructures the roadmap plugin by removing its duplicated domain logic (roadmap store, ordering, handoff, and types — ~3,000 lines deleted) and completing the plugin SDK scaffold with proper route status/body contracts and type exports. It also introduces eval settings infrastructure wit
Fusion-Task-Id: FN-3638
Merges the roadmap plugin scaffold (FN-3636): a new `plugins/fusion-plugin-roadmap` workspace with domain types (`roadmap-types.ts`), a store layer (`roadmap-store.ts`, `roadmap-ordering.ts`, `roadmap-handoff.ts`), and comprehensive test suites. Also lands graph position persistence for the dependen
Fusion-Task-Id: FN-3636
