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/context/AppContext.test.tsx

@@ -131,7 +131,6 @@ describe("useAppContext", () => {
 				shoutrrrStockReminders: true,
 				shoutrrrIntakeReminders: true,
 				stockCalculationMode: "automatic",
-				shareStockStatus: true,
 				shareMedicationOverview: false,
 				expiryWarningDays: 30,
 			},
@@ -171,7 +170,6 @@ describe("useAppContext", () => {
 				shoutrrrStockReminders: true,
 				shoutrrrIntakeReminders: true,
 				stockCalculationMode: "automatic",
-				shareStockStatus: true,
 				shareMedicationOverview: false,
 				expiryWarningDays: 30,
 			},