fix(v0.5.0): pre-release polish from full-codebase review

- Plugin.cs: mark RetentionSweepRunning volatile so the ImGui thread
  reads the latest value without a stale register-cached copy
- EmoteCache.cs: reset State to Unloaded on exception so a later
  trigger can retry instead of being blocked by the early-out
- Settings.cs: switch the SaveAndClose / Discard buttons to Allman
  bracing for consistency with the rest of the file, and include the
  ItemSpacing in the Ko-fi-button right-edge calculation
- Privacy.cs: add a saved-policy hint above the manual retention
  Ctrl+Shift button so the existing Cleanup wording pattern is
  matched here too
- HellionStrings: drop seven unreferenced keys (Theme_Heading,
  Migration_Notification_*, Migration_Webinterface_Removed_*,
  AutoTellTabs_Migration_*) and their EN/DE values, add the new
  Retention_Help_SavedNote string

ChatTwo/Ui/Settings.cs

@@ -110,14 +110,16 @@ public sealed class SettingsWindow : Dalamud.Interface.Windowing.Window
 
         ImGui.SameLine();
 
-        if (ImGui.Button(Language.Settings_SaveAndClose)) {
+        if (ImGui.Button(Language.Settings_SaveAndClose))
+        {
             save = true;
             IsOpen = false;
         }
 
         ImGui.SameLine();
 
-        if (ImGui.Button(Language.Settings_Discard)) {
+        if (ImGui.Button(Language.Settings_Discard))
+        {
             IsOpen = false;
         }
 
@@ -131,7 +133,7 @@ public sealed class SettingsWindow : Dalamud.Interface.Windowing.Window
         {
             var buttonWidth = ImGui.CalcTextSize(buttonLabel).X + ImGui.GetStyle().FramePadding.X * 2;
             var buttonWidth2 = ImGui.CalcTextSize(buttonLabel2).X + ImGui.GetStyle().FramePadding.X * 2;
-            ImGui.SameLine(ImGui.GetContentRegionAvail().X - buttonWidth - buttonWidth2);
+            ImGui.SameLine(ImGui.GetContentRegionAvail().X - buttonWidth - buttonWidth2 - ImGui.GetStyle().ItemSpacing.X);
 
             if (ImGui.Button(buttonLabel2))
                 Dalamud.Utility.Util.OpenLink("https://ko-fi.com/infiii");