Add distributed settings and workspace import/export (M5)

src/app/modals/modal-registry.ts

@@ -10,8 +10,10 @@
  * single shell-level Save/Cancel doesn't fit). The registry therefore omits
  * `hasError`/`getError` (validity is the modal's own concern) and keeps only
  * `getState` for unsaved-change detection on close. The registry is a partial
- * map: modals land milestone by milestone (settings/about/donate → M5/M6,
- * chartBuilder → M4), so only the implemented ones are registered here.
+ * map: modals land milestone by milestone (about/donate → M6, chartBuilder → M4),
+ * so only the implemented ones are registered here. Settings is deliberately NOT
+ * a modal — preferences are distributed to per-pane disclosure popovers (spec §07;
+ * see components/SettingsPopover).
  */
 
 import type { ComponentType } from 'react';