feat: rebrand to MMD PDF, single corporate theme, and remove original text under an edit

- Services/PdfRedactText.cs: strip text whose origin falls inside a CoverAnnotation
  from the page content stream at save time, hooked into PdfBurn.DrawAnnotationsIntoDoc.
  Fixes edited values staying recoverable by text extraction.
- Themes/MMD.xaml replaces all thirteen themes; picker and accent strip removed; no dark mode.
- Rename KillerPDF -> MMD PDF across code, resources, packaging and locale strings; new icon.
- Remove the upstream author credit and the in-app install button.

Shell/About.cs

@@ -3,9 +3,9 @@ using System.Windows;
 using System.Windows.Documents;
 using System.Windows.Input;
 using System.Windows.Media;
-using KillerPDF.Features;
+using MmdPdf.Features;
 
-namespace KillerPDF
+namespace MmdPdf
 {
     /// <summary>
     /// The About overlay's window half: the IAboutHost implementation that maps the controller's
@@ -13,9 +13,9 @@ namespace KillerPDF
     /// handlers. All the logic - signature, hashing, update check, self-update - lives in
     /// <see cref="AboutController"/>.
     ///
-    /// NOTE: this stays "namespace KillerPDF" rather than KillerPDF.Shell, because it is a partial
+    /// NOTE: this stays "namespace MmdPdf" rather than MmdPdf.Shell, because it is a partial
     /// of MainWindow and every partial of a class must share one namespace. It moves to
-    /// KillerPDF.Shell when MainWindow itself does.
+    /// MmdPdf.Shell when MainWindow itself does.
     /// </summary>
     public partial class MainWindow : IAboutHost
     {
@@ -123,7 +123,7 @@ namespace KillerPDF
                 FontSize   = 27.3,
                 Foreground = Res("AccentLogo")
             });
-            hl.Click += (_, _) => AboutController.OpenUrl("https://killerpdf.net");
+            hl.Click += (_, _) => AboutController.OpenUrl("https://baobab-ts.com");
             AboutLogoBlock.Inlines.Add(hl);
 
             // The shadow copy mirrors the real runs exactly (sizes, weights, fonts), so the blur
@@ -176,7 +176,7 @@ namespace KillerPDF
 
             AddText(pre);
             AboutTaglineBlock.Inlines.Add(
-                AccentLink("Killer Tools", () => AboutController.OpenUrl("https://killertools.net")));
+                AccentLink("Killer Tools", () => AboutController.OpenUrl("https://baobab-ts.com")));
             AddText(suf);
         }