- Add typed dev server models and constants for configs, session state, runtime metadata, and bounded log history
- Add JSON persistence helpers for .fusion/devserver.json with tolerant parsing and session reconstruction
- Add dev command auto-detection across root and workspace package.json scripts with framework inference and priority sorting
- Implement DevServerManager lifecycle controls, preview URL detection, port probing fallback, and singleton manager helpers
- Add Vitest coverage for devserver types, detection/persistence behavior, and manager lifecycle/events
