API: usePersistedSetting Hook/Composable for Blazor

### Why
Develop ergonomic Blazor APIs for screen/components to use persistent state declaratively. Should work for MudBlazor and raw Blazor, encapsulate read/write, handle hydration (load-once), debouncing, etc.

### Acceptance Criteria
- Provide composable (hook/service/component) that loads, exposes, and sets settings transparently
- Update (and debounce) pattern that doesn’t break Blazor render loop
- Can be used for both session and local persistence
- Example used in shell, workflow designer, and workflow table
- Optional: allow setting resets in-UI