feat(tabs): add dedicated System tab to default layout

Split the technical/notification streams (System, Error, Echo, Debug,
NPC announcements, login/logout, retainer sales, gathering system,
glamour notifications, sign messages, alarms, orchestrion, message
book, random number, progress) out of the General tab into their own
System tab. General now shows player conversation plus the active
gameplay events (loot rolls, crafting, gathering, NPC dialogue, party
finder pings) without burying chat under technical chatter.

ChatTwo/Resources/HellionStrings.Designer.cs

@@ -233,6 +233,7 @@ internal class HellionStrings
     internal static string Settings_Information_Changelog_Heading => Get(nameof(Settings_Information_Changelog_Heading));
 
     // Hellion Chat — Default tab presets (channel-themed)
+    internal static string Tabs_Presets_System => Get(nameof(Tabs_Presets_System));
     internal static string Tabs_Presets_FreeCompany => Get(nameof(Tabs_Presets_FreeCompany));
     internal static string Tabs_Presets_Party => Get(nameof(Tabs_Presets_Party));
     internal static string Tabs_Presets_Beginner => Get(nameof(Tabs_Presets_Beginner));

ChatTwo/Resources/HellionStrings.de.resx

@@ -528,6 +528,9 @@
   </data>
 
   <!-- Hellion Chat — Default-Tab-Presets (kanalspezifisch) -->
+  <data name="Tabs_Presets_System" xml:space="preserve">
+    <value>System</value>
+  </data>
   <data name="Tabs_Presets_FreeCompany" xml:space="preserve">
     <value>Free Company</value>
   </data>

ChatTwo/Resources/HellionStrings.resx

@@ -528,6 +528,9 @@
   </data>
 
   <!-- Hellion Chat — Default tab presets (channel-themed) -->
+  <data name="Tabs_Presets_System" xml:space="preserve">
+    <value>System</value>
+  </data>
   <data name="Tabs_Presets_FreeCompany" xml:space="preserve">
     <value>Free Company</value>
   </data>