fix(config): guard the shared config maps, restore lost fields in Tab.Clone

TabsListLock never covered ChatColours, PrivacyPersistChannels or
RetentionPerChannelDays, yet the settings UI mutates them from the draw thread
while the retention thread can be serializing the same config. Adding a new key
to a dictionary or a new element to a set invalidates a running enumeration, so
this could throw from inside JsonConvert.SerializeObject.

Not a corner case: the colour picker lists 66 channels but only 25 ship with a
default, so the first edit of any of the remaining ones inserts a new key -- and
the reset button removes a key, which makes the next edit a fresh insert again.

The readers matter as much as the writers. IsAllowedForStorage runs per message
on the worker thread and asks PrivacyPersistChannels whether a channel may be
stored; a Contains racing an Add that resizes buckets can answer wrong, and that
answer decides whether a message is written to disk. The retention sweep
enumerates RetentionPerChannelDays on the framework thread while the wizard can
clear it -- Clear does not throw there, it just cuts the enumeration short, so
the sweep would run on half a policy.

New ConfigMapsLock covers all of it. It sits inside TabsListLock (that edge is
real, AutoTellTabsService calls SaveConfig while holding the tabs lock), never
the other way round -- so every call site closes the lock before saving.

Tab.Clone silently dropped Icon and ChatCodes, both serialized. A reflection
test now walks the serialized fields so a future one cannot slip past.

Also: CurrentTab read Count and [0] as two separate accesses.

HellionChat/Ui/Components/Settings/ChatColourPicker.cs

@@ -71,7 +71,8 @@ internal sealed class ChatColourPicker
                     )
                 )
                 {
-                    Plugin.Config.ChatColours.Remove(type);
+                    lock (_plugin.ConfigMapsLock)
+                        Plugin.Config.ChatColours.Remove(type);
                     commit = true;
                 }
 
@@ -86,7 +87,8 @@ internal sealed class ChatColourPicker
                 )
                 {
                     var gameColour = _plugin.Functions.Chat.GetChannelColor(type);
-                    Plugin.Config.ChatColours[type] = gameColour ?? type.DefaultColor() ?? 0;
+                    lock (_plugin.ConfigMapsLock)
+                        Plugin.Config.ChatColours[type] = gameColour ?? type.DefaultColor() ?? 0;
                     commit = true;
                 }
 
@@ -97,7 +99,10 @@ internal sealed class ChatColourPicker
                     : ColourUtil.RgbaToVector3(type.DefaultColor() ?? 0);
                 if (ImGui.ColorEdit3(type.Name(), ref vec, ImGuiColorEditFlags.NoInputs))
                 {
-                    Plugin.Config.ChatColours[type] = ColourUtil.Vector3ToRgba(vec);
+                    // First edit of a channel without a default inserts a NEW key --
+                    // that is the case that invalidates a running enumeration.
+                    lock (_plugin.ConfigMapsLock)
+                        Plugin.Config.ChatColours[type] = ColourUtil.Vector3ToRgba(vec);
                     liveOnly = true;
                 }
                 if (ImGui.IsItemDeactivatedAfterEdit())
@@ -155,7 +160,8 @@ internal sealed class ChatColourPicker
     private void ApplyPreset(ChatColourPreset preset)
     {
         foreach (var (channel, colour) in preset.Colours)
-            Plugin.Config.ChatColours[channel] = colour;
+            lock (_plugin.ConfigMapsLock)
+                Plugin.Config.ChatColours[channel] = colour;
         ApplyChatColourChange();
     }
 
@@ -226,7 +232,8 @@ internal sealed class ChatColourPicker
             if (ImGui.Button(HellionStrings.Settings_Themes_ApplyChatColors_Apply))
             {
                 foreach (var kvp in themeChatColors.Channels)
-                    Plugin.Config.ChatColours[kvp.Key] = kvp.Value;
+                    lock (_plugin.ConfigMapsLock)
+                        Plugin.Config.ChatColours[kvp.Key] = kvp.Value;
                 _applyDismissedFor = active.Slug;
                 ApplyChatColourChange();
             }

HellionChat/Ui/Components/Settings/Tabs/ChatTab.cs

@@ -84,13 +84,18 @@ internal sealed class ChatTab
             var present = Plugin.Config.PrivacyPersistChannels.Contains(ct);
             if (ImGui.Checkbox($"{label}##persist-{label}", ref present))
             {
-                if (present)
+                // Lock closes before SaveConfig: taking ConfigMapsLock across a save
+                // would invert the lock order (SaveConfig can reach TabsListLock).
+                lock (_plugin.ConfigMapsLock)
                 {
-                    Plugin.Config.PrivacyPersistChannels.Add(ct);
-                }
-                else
-                {
-                    Plugin.Config.PrivacyPersistChannels.Remove(ct);
+                    if (present)
+                    {
+                        Plugin.Config.PrivacyPersistChannels.Add(ct);
+                    }
+                    else
+                    {
+                        Plugin.Config.PrivacyPersistChannels.Remove(ct);
+                    }
                 }
                 _plugin.SaveConfig();
             }

HellionChat/Ui/Components/Settings/Tabs/DataPrivacyTab.cs

@@ -81,13 +81,17 @@ internal sealed class DataPrivacyTab
             var present = Plugin.Config.PrivacyPersistChannels.Contains(ct);
             if (ImGui.Checkbox($"{label}##privacy-persist-{label}", ref present))
             {
-                if (present)
+                // Lock closes before the save below, see ChatTab for the ordering.
+                lock (_plugin.ConfigMapsLock)
                 {
-                    Plugin.Config.PrivacyPersistChannels.Add(ct);
-                }
-                else
-                {
-                    Plugin.Config.PrivacyPersistChannels.Remove(ct);
+                    if (present)
+                    {
+                        Plugin.Config.PrivacyPersistChannels.Add(ct);
+                    }
+                    else
+                    {
+                        Plugin.Config.PrivacyPersistChannels.Remove(ct);
+                    }
                 }
                 _plugin.SaveConfig();
             }

HellionChat/Ui/FirstRunWizard.cs

@@ -655,7 +655,10 @@ public sealed class FirstRunWizard : Window
         Plugin.Config.PrivacyPersistUnknownChannels = true;
 
         Plugin.Config.RetentionEnabled = false;
-        Plugin.Config.RetentionPerChannelDays.Clear();
+        // Clear does not throw during enumeration, it just cuts it short -- the
+        // retention sweep would then run on half a policy.
+        lock (Plugin.ConfigMapsLock)
+            Plugin.Config.RetentionPerChannelDays.Clear();
     }
 
     // Test-only entry point so SelfTests/WizardStateSmokeStep can advance