Adds an assertion for the suggestion route error contract in the roadmap routes test file, completing the test coverage for that endpoint.
Fusion-Task-Id: FN-3163
The merge completes FN-3160 by making the roadmap route context plugin-owned, moving `roadmap-routes` and `roadmap-suggestions` logic from the dashboard into `fusion-plugin-roadmap` with updated plugin-loader integration. It also includes FN-3755's shared state snapshot support for mesh sync hardeni
Fusion-Task-Id: FN-3160