fix: build Windows — nettoyer python-embed avant extraction + supprimer champs NSIS invalides

- build-windows.bat: rmdir python-embed avant téléchargement (évite conflit Expand-Archive)
- tauri.conf.json: retirer shortcutName et createDesktopShortcut (n'existent pas dans NsisConfig Tauri v2)

desktop/build-windows.bat

@@ -20,6 +20,7 @@ REM ── 2. Préparer Python 3.11 embed ────────────
 echo [2/6] Preparing Python embed...
 if not exist "python-embed\python.exe" (
     echo 📥 Downloading Python 3.11 embed...
+    if exist "python-embed" rmdir /s /q "python-embed"
     curl -L -o python-embed.zip "https://www.python.org/ftp/python/3.11.9/python-3.11.9-embed-amd64.zip"
     powershell Expand-Archive -Path python-embed.zip -DestinationPath python-embed\
     del python-embed.zip

desktop/tauri.conf.json

@@ -58,8 +58,6 @@
       "nsis": {
         "installMode": "currentUser",
         "installerIcon": "icons/icon.ico",
-        "shortcutName": "ObsiGate",
-        "createDesktopShortcut": true,
         "startMenuFolder": "ObsiGate"
       }
     },