feat: remove Show All navigation card from entity grids

- Remove ShowAllCard component and all related functionality
- Remove showAllRoute, showAllQueryParams, and hideShowAll props
- Remove shouldShowAll computed property from EntityGrid
- Clean up ShowAll-related code from EntitySelectionStep and GiftedDialog
- Delete ShowAllCard.vue component file
- Update component documentation to reflect removal

This simplifies the entity selection interface by removing the navigation
card that allowed users to view all entities in a separate view.

src/components/GiftedDialog.vue

@@ -29,7 +29,6 @@
         :unit-code="unitCode"
         :offer-id="offerId"
         :notify="$notify"
-        :hide-show-all="hideShowAll"
         @entity-selected="handleEntitySelected"
         @cancel="cancel"
       />
@@ -117,7 +116,6 @@ export default class GiftedDialog extends Vue {
   @Prop() fromProjectId = "";
   @Prop() toProjectId = "";
   @Prop() isFromProjectView = false;
-  @Prop() hideShowAll = false;
   @Prop({ default: "person" }) giverEntityType = "person" as
     | "person"
     | "project";