Feature: Persist Workflow Table/Grid State

### Why
Persist grid/table state (columns, filters, sorting, page size, etc.) for workflow list and other screens. Use new persistence service to store state keyed by user/screen/scope, and restore reliably on revisit. Last modified and/or last executed column enhancements tracked in #216.

### Acceptance Criteria
- Table state (columns, sorting, filters, page size) is saved on mutation
- Table state is restored when user returns to page
- User can reset table state
- Table state saves to localStorage by default
- (Separate: last modified/last executed tracked by #216)

### Deliverables
- PR updating all workflow-related tables/lists
- Example usage of hook/service
- Unit/E2E test or manual validation plan