fix: remove dead shareStockStatus gating from shared medication overview (#436)

The shareStockStatus UI toggle was replaced by shareMedicationOverview in
commit e0fb77d, but the backend gating logic was left intact. Users who
had previously set shareStockStatus=false were stuck with empty stock
values ('-') on the shared medication overview with no UI to change it.

- Remove showStockStatus parameter from buildSharedMedicationOverview()
- Remove visibility gating that nullified stock fields
- Remove shareStockStatus from settings API responses and PUT schema
- Remove shareStockStatus from frontend types, hooks, and context
- Clean up all related test fixtures and dead test cases
- DB column share_stock_status retained (never remove columns)

frontend/src/test/components/SharedSchedule.test.tsx

@@ -18,7 +18,6 @@ function createSharedData() {
 		sharedBy: "Owner",
 		takenBy: "Max",
 		scheduleDays: 30,
-		shareStockStatus: true,
 		medications: [],
 	};
 }
@@ -64,7 +63,6 @@ function createSharedDataWithTodayDose() {
 		takenBy: "Max",
 		scheduleDays: 30,
 		automaticDoseId: `1-0-${dateOnlyMs}`,
-		shareStockStatus: true,
 		medications: [
 			{
 				id: 1,