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.

MmdPdf.Tests/AnnotationRotateTests.cs

@@ -0,0 +1,114 @@
+using System.Windows;
+using MmdPdf.Services;
+using Xunit;
+
+namespace MmdPdf.Tests;
+
+// #169: rotating a page must keep its overlay annotations and turn them with the page.
+// The mapping runs in render-dim space; a +90 turn takes frame (W, H) to (H, W), so
+// round-trip tests swap the frame between passes exactly as the live reload does.
+public sealed class AnnotationRotateTests
+{
+    private const double W = 800, H = 600;
+
+    [Fact]
+    public void Highlight_QuarterTurn_TurnsWithTheContent()
+    {
+        var ha = new HighlightAnnotation { Bounds = new Rect(10, 20, 100, 40) };
+        AnnotationRotate.Remap([ha], 90, W, H);
+
+        // Corners (10,20)-(110,60) map to (580,10)-(540,110): the region swaps its axes.
+        Assert.Equal(540, ha.Bounds.X, 3);
+        Assert.Equal(10, ha.Bounds.Y, 3);
+        Assert.Equal(40, ha.Bounds.Width, 3);
+        Assert.Equal(100, ha.Bounds.Height, 3);
+    }
+
+    [Fact]
+    public void Highlight_FourQuarterTurns_IsIdentity()
+    {
+        var start = new Rect(10, 20, 100, 40);
+        var ha = new HighlightAnnotation { Bounds = start };
+        AnnotationRotate.Remap([ha], 90, W, H);
+        AnnotationRotate.Remap([ha], 90, H, W);
+        AnnotationRotate.Remap([ha], 90, W, H);
+        AnnotationRotate.Remap([ha], 90, H, W);
+        Assert.Equal(start, ha.Bounds);
+    }
+
+    [Fact]
+    public void Highlight_TurnThenCounterTurn_IsIdentity()
+    {
+        var start = new Rect(33, 44, 55, 66);
+        var ha = new HighlightAnnotation { Bounds = start };
+        AnnotationRotate.Remap([ha], 90, W, H);
+        AnnotationRotate.Remap([ha], -90, H, W);
+        Assert.Equal(start, ha.Bounds);
+    }
+
+    [Fact]
+    public void Highlight_TwoQuarterTurns_MatchHalfTurn()
+    {
+        var a = new HighlightAnnotation { Bounds = new Rect(10, 20, 100, 40) };
+        var b = new HighlightAnnotation { Bounds = new Rect(10, 20, 100, 40) };
+        AnnotationRotate.Remap([a], 90, W, H);
+        AnnotationRotate.Remap([a], 90, H, W);
+        AnnotationRotate.Remap([b], 180, W, H);
+        Assert.Equal(b.Bounds, a.Bounds);
+    }
+
+    [Fact]
+    public void TextBox_KeepsSize_CenterFollowsThePage()
+    {
+        var ta = new TextAnnotation { Position = new Point(10, 70), Width = 100, Height = 40 };
+        AnnotationRotate.Remap([ta], 90, W, H);
+
+        // Center (60,90) maps to (510,60); the box keeps 100x40 around it.
+        Assert.Equal(460, ta.Position.X, 3);
+        Assert.Equal(40, ta.Position.Y, 3);
+        Assert.Equal(100, ta.Width, 3);
+        Assert.Equal(40, ta.Height, 3);
+    }
+
+    [Fact]
+    public void UprightTextBoxNearLongEdge_IsClampedInsideRotatedPage()
+    {
+        // Fully inside the old 800x600 page. Keeping this tall box upright after a clockwise turn
+        // would put its bottom at 870 on the new 600x800 page unless the remap clamps it.
+        var ta = new TextAnnotation { Position = new Point(750, 100), Width = 40, Height = 200 };
+        AnnotationRotate.Remap([ta], 90, W, H);
+
+        Assert.Equal(380, ta.Position.X, 3);
+        Assert.Equal(600, ta.Position.Y, 3);
+        Assert.InRange(ta.Position.X + ta.Width, 0, H);
+        Assert.InRange(ta.Position.Y + ta.Height, 0, W);
+    }
+
+    [Fact]
+    public void UprightPlacedItemNearLongEdge_IsClampedInsideRotatedPage()
+    {
+        var image = new ImageAnnotation
+        {
+            Position = new Point(750, 100),
+            SourceWidth = 40,
+            SourceHeight = 200,
+            Scale = 1
+        };
+
+        AnnotationRotate.Remap([image], 90, W, H);
+
+        Assert.Equal(380, image.Position.X, 3);
+        Assert.Equal(600, image.Position.Y, 3);
+        Assert.InRange(image.Position.X + image.SourceWidth * image.Scale, 0, H);
+        Assert.InRange(image.Position.Y + image.SourceHeight * image.Scale, 0, W);
+    }
+
+    [Fact]
+    public void InkPoints_MapPerPoint()
+    {
+        var ia = new InkAnnotation { Points = [new Point(0, 0), new Point(100, 50)] };
+        AnnotationRotate.Remap([ia], 90, W, H);
+        Assert.Equal(new Point(H, 0), ia.Points[0]);
+        Assert.Equal(new Point(H - 50, 100), ia.Points[1]);
+    }
+}