- Add ConfigProfile and ConfigProfileInclude data models with migrations
- Implement profile resolver service with ordered includes and merge rules
- Add profile CRUD API with validation, compatibility, and cycle detection
- Add instance API plumbing for profile selection on create/start/restart
- Add resolved profile preview and default resolution APIs
- Add frontend config profile API client and management UI
- Add launch/restart profile selection UI
- Add backend integration and unit tests (31 passing)
OpenSpec: add-config-profiles
Quality gates: ruff, TypeScript compile, 31 tests passing
- Backend: Send ping every 30s from WebSocket endpoint
- Frontend: Respond to pings with pongs, detect missed pings (60s timeout)
- Update type definitions to include 'resetting' status
Refs: persistent-terminal-sessions task 6.4
alex