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.

build/build-portable.ps1

@@ -10,14 +10,14 @@ $ErrorActionPreference = 'Stop'
 Set-StrictMode -Version Latest
 
 $projectDir = Split-Path -Parent $PSScriptRoot
-$appProject = Join-Path $projectDir 'KillerPDF.csproj'
-$launcherProject = Join-Path $projectDir 'Packaging\KillerLauncher\KillerLauncher.csproj'
+$appProject = Join-Path $projectDir 'MmdPdf.csproj'
+$launcherProject = Join-Path $projectDir 'Packaging\MmdPdfLauncher\MmdPdfLauncher.csproj'
 $artifactRoot = Join-Path $projectDir "bin\$Configuration\net48\portable-package"
 $payloadDir = Join-Path $artifactRoot 'payload'
 $payloadZip = Join-Path $artifactRoot 'payload.zip'
 $launcherOutput = Join-Path $artifactRoot 'launcher'
 $publicDir = Join-Path $projectDir "bin\$Configuration\net48\publish"
-$publicExe = Join-Path $publicDir 'KillerPDF.exe'
+$publicExe = Join-Path $publicDir 'MmdPdf.exe'
 
 if (-not $RepackOnly) {
     if ([IO.Directory]::Exists($artifactRoot)) { [IO.Directory]::Delete($artifactRoot, $true) }
@@ -31,10 +31,10 @@ if ([IO.Directory]::Exists($launcherOutput)) { [IO.Directory]::Delete($launcherO
 $versionXml = [xml](Get-Content -Raw -LiteralPath $appProject)
 $versionNode = $versionXml.SelectSingleNode('/Project/PropertyGroup/Version')
 $version = if ($versionNode) { [string]$versionNode.InnerText } else { '' }
-if (-not $version) { throw 'KillerPDF.csproj has no Version.' }
+if (-not $version) { throw 'MmdPdf.csproj has no Version.' }
 
 if (-not $RepackOnly) {
-    Write-Host "==> Building loose KillerPDF payload $version..." -ForegroundColor Cyan
+    Write-Host "==> Building loose MmdPdf payload $version..." -ForegroundColor Cyan
     & dotnet publish $appProject -c $Configuration `
         -p:KillerPayloadBuild=true `
         -p:PublishDir="$payloadDir\"
@@ -49,7 +49,7 @@ if (-not $RepackOnly) {
     # The PDF file-type icon is a loose installed asset even though the application also embeds it.
     [IO.File]::Copy((Join-Path $projectDir 'Resources\pdf-file.ico'),
                     (Join-Path $payloadDir 'pdf-file.ico'), $true)
-} elseif (-not [IO.File]::Exists((Join-Path $payloadDir 'KillerPDF.App.exe'))) {
+} elseif (-not [IO.File]::Exists((Join-Path $payloadDir 'MmdPdf.App.exe'))) {
     throw 'RepackOnly requested but the prepared payload is missing.'
 }
 
@@ -67,7 +67,7 @@ if ($payloadDifference.Count -gt 0) {
     $details = ($payloadDifference | ForEach-Object { "$($_.SideIndicator) $($_.InputObject)" }) -join [Environment]::NewLine
     throw "Payload file set changed. Review dependencies and update build\payload-files.txt deliberately:`n$details"
 }
-foreach ($required in 'KillerPDF.App.exe', 'pdfium.dll', 'PdfSharpCore.dll', 'System.Text.Json.dll') {
+foreach ($required in 'MmdPdf.App.exe', 'pdfium.dll', 'PdfSharpCore.dll', 'System.Text.Json.dll') {
     if ($actualPayloadNames -notcontains $required) {
         throw "Required loose payload file is missing ($required). Costura/Fody may have run accidentally."
     }
@@ -105,15 +105,15 @@ finally { $zipStream.Dispose() }
 
 Write-Host "==> Building the public portable launcher..." -ForegroundColor Cyan
 & dotnet publish $launcherProject -c $Configuration `
-    -p:LauncherAssemblyName=KillerPDF `
+    -p:LauncherAssemblyName=MmdPdf `
     -p:LauncherVersion=$version `
-    -p:LauncherIcon="$(Join-Path $projectDir 'Resources\kp-icon.ico')" `
+    -p:LauncherIcon="$(Join-Path $projectDir 'Resources\mmd-icon.ico')" `
     -p:PayloadZip="$payloadZip" `
     -p:AllowUnsignedInstall="$(!$RequireSignature)" `
     -p:PublishDir="$launcherOutput\"
 if ($LASTEXITCODE -ne 0) { throw 'Launcher build failed.' }
 
-$builtLauncher = Join-Path $launcherOutput 'KillerPDF.exe'
+$builtLauncher = Join-Path $launcherOutput 'MmdPdf.exe'
 if (-not [IO.File]::Exists($builtLauncher)) { throw "Launcher output is missing: $builtLauncher" }
 [IO.File]::Copy($builtLauncher, $publicExe, $true)