chore: Windows build, Inno Setup installer, MSIX support, README güncellemesi

- flutter build windows --release başarılı
- Inno Setup installer (dist/imajviewer_setup_1.0.0.exe)
- MSIX paketi mevcut (imzasız, Developer Mode gerekli)
- pubspec.yaml: msix_config eklendi
- .gitignore: dist/, *.pfx, *.cer, *.msix
- README.md: Windows kurulum seçenekleri güncellendi

.gitignore

@@ -43,3 +43,9 @@ app.*.map.json
 /android/app/debug
 /android/app/profile
 /android/app/release
+
+# Windows installer output
+/dist/
+*.pfx
+*.cer
+*.msix