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

pubspec.yaml

@@ -1,8 +1,16 @@
 name: imajviewer
-description: "Ultra hafif Linux görüntü izleyici"
+description: "Ultra hafif görüntü izleyici"
 publish_to: 'none'
 version: 1.0.0+1
 
+msix_config:
+  display_name: ImajViewer
+  publisher_display_name: imajviewer
+  identity_name: imajviewer.imajviewer
+  logo_path: C:/projects/imajviewer/windows/runner/resources/app_icon.ico
+  install_certificate: false
+  sign_msix: false
+
 environment:
   sdk: ^3.12.2
 
@@ -13,6 +21,7 @@ dependencies:
   file_picker: ^8.0.0
   path: ^1.9.0
   desktop_drop: ^0.7.1
+  msix: ^3.18.0
 
 dev_dependencies:
   flutter_test: