chore: comments, second pass -- the task codes the first pass missed

The first sweep matched a character class that swallowed the digit, so a bare
B1 slipped through while B1-2 was caught. Searching the whole A-Z space instead
of guessing prefixes turned up 130-odd more: B0 through B6, C2, C3, D1, H2, M6,
P7, P8, T2, W2, plus GP-04, KB-01, OD-1, PM-1, PM-3, SEC-01, TR-4, TR-7, UI-11,
UI-12, XC-8 and API-3.

Kept deliberately: 41 B4 01 is a byte signature, "N0" a format string,
#L119-L128 a source anchor, LS4/LS6 are linkshells, and A=FF B=0C G=41 R=C2
explains a colour-channel order. Those look like codes and are not.

Also translated the eight German comments left in the theme files and
ImGuiUtil. Seven of them described what a palette does to which channel, which
is worth reading -- just not in a second language in an otherwise English
codebase.

HellionChat/Ui/InputPreview.cs

@@ -168,7 +168,7 @@ internal sealed class InputPreview : Window
         {
             ImGui.TextUnformatted(Language.Options_Preview_Header);
 
-            // Primary path (A2) resets the Lender counter in MainWindow.Draw();
+            // Primary path resets the Lender counter in MainWindow.Draw();
             // this fallback covers the edge-case where MainWindow is closed but
             // InputPreview is still open, preventing handler pool growth.
             if (!_mainWindow.IsOpen)