Migrate the Fusion dashboard's vitest configuration to use the new `test.projects` API in the roadmap plugin, with plugin view registration updates and typecheck fixes in the dashboard components.
Fusion-Task-Id: FN-3898
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