uplink locking/unlocking, minor pda refactor (#15842)

Co-authored-by: deltanedas <@deltanedas:kde.org>

Content.Server/Store/Systems/StoreSystem.Ui.cs

@@ -1,5 +1,6 @@
 using Content.Server.Actions;
 using Content.Server.Administration.Logs;
+using Content.Server.PDA.Ringer;
 using Content.Server.Stack;
 using Content.Server.Store.Components;
 using Content.Server.UserInterface;
@@ -49,6 +50,17 @@ public sealed partial class StoreSystem
         UpdateUserInterface(user, storeEnt, component);
     }
 
+    /// <summary>
+    /// Closes the store UI for everyone, if it's open
+    /// </summary>
+    public void CloseUi(EntityUid uid, StoreComponent? component = null)
+    {
+        if (!Resolve(uid, ref component))
+            return;
+
+        _ui.TryCloseAll(uid, StoreUiKey.Key);
+    }
+
     /// <summary>
     /// Updates the user interface for a store and refreshes the listings
     /// </summary>
@@ -83,7 +95,9 @@ public sealed partial class StoreSystem
         // TODO: if multiple users are supposed to be able to interact with a single BUI & see different
         // stores/listings, this needs to use session specific BUI states.
 
-        var state = new StoreUpdateState(component.LastAvailableListings, allCurrency);
+        // only tell operatives to lock their uplink if it can be locked
+        var showFooter = HasComp<RingerUplinkComponent>(store);
+        var state = new StoreUpdateState(component.LastAvailableListings, allCurrency, showFooter);
         _ui.SetUiState(ui, state);
     }