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/context/AppContext.tsx

@@ -792,7 +792,6 @@ export function AppProvider({ children }: { children: React.ReactNode }) {
 			settings.reminderRepeatIntervalMinutes !== savedSettings.reminderRepeatIntervalMinutes ||
 			settings.maxNaggingReminders !== savedSettings.maxNaggingReminders ||
 			settings.stockCalculationMode !== savedSettings.stockCalculationMode ||
-			settings.shareStockStatus !== savedSettings.shareStockStatus ||
 			settings.shareMedicationOverview !== savedSettings.shareMedicationOverview ||
 			settings.upcomingTodayOnly !== savedSettings.upcomingTodayOnly ||
 			settings.shareScheduleTodayOnly !== savedSettings.shareScheduleTodayOnly ||