fix: nettoyer warning state_clone + xcopy /Y + taskkill avant copie runtime

- main.rs: supprimer state_clone unused dans restart_backend
- build-windows.bat: taskkill /F python.exe avant xcopy (évite Access denied)
- build-windows.bat: /Y sur xcopy (pas de prompt interactif)
- build-windows.bat: 2>nul sur rmdir (silencieux si dossier absent)

desktop/build-windows.bat

@@ -48,13 +48,15 @@ echo ✅ Build successful
 
 REM ── 4. Copier le runtime à côté de l'exécutable ───────────────
 echo [4/5] Copying runtime to output dir...
+REM Kill any leftover backend from a previous run
+taskkill /F /IM python.exe /FI "WINDOWTITLE eq *" 2>nul
 set "OUTDIR=target\x86_64-pc-windows-msvc\release"
-if exist "%OUTDIR%\python-embed" rmdir /s /q "%OUTDIR%\python-embed"
-if exist "%OUTDIR%\backend" rmdir /s /q "%OUTDIR%\backend"
-if exist "%OUTDIR%\frontend" rmdir /s /q "%OUTDIR%\frontend"
-xcopy /E /I /Q "python-embed" "%OUTDIR%\python-embed"
-xcopy /E /I /Q "..\backend" "%OUTDIR%\backend"
-xcopy /E /I /Q "..\frontend" "%OUTDIR%\frontend"
+if exist "%OUTDIR%\python-embed" rmdir /s /q "%OUTDIR%\python-embed" 2>nul
+if exist "%OUTDIR%\backend" rmdir /s /q "%OUTDIR%\backend" 2>nul
+if exist "%OUTDIR%\frontend" rmdir /s /q "%OUTDIR%\frontend" 2>nul
+xcopy /E /I /Q /Y "python-embed" "%OUTDIR%\python-embed"
+xcopy /E /I /Q /Y "..\backend" "%OUTDIR%\backend"
+xcopy /E /I /Q /Y "..\frontend" "%OUTDIR%\frontend"
 
 REM Add parent directory to Python path so 'import backend' works at runtime
 echo ..>> "%OUTDIR%\python-embed\python311._pth"

desktop/src/main.rs

@@ -256,9 +256,7 @@ fn restart_backend(state: tauri::State<BackendProcess>) -> Result<String, String
             *guard = Some(new_child);
             drop(guard);
 
-            // Wait for it to become ready (fire and forget with UI poll)
-            let state_clone = state.inner().clone();
-            // Can't clone state directly, use a flag pattern
+            // Fire and forget — the monitoring loop will detect when it's ready
             info!("Backend restart initiated");
             Ok("restarting".to_string())
         }