fix: erreurs de compilation — MutexGuard Send, i32/u32→f64, exe_dir Option, warnings

- check_backend_health: dropper MutexGuard avant .await (Send bound)
- pos.x/y (i32) → as f64, size.width/height (u32) → as f64
- current_exe: .ok().and_then() au lieu de .and_then() (Option vs Result)
- Supprimer state_clone unused + _app pour save_window_state

desktop/src/main.rs

@@ -272,13 +272,14 @@ fn restart_backend(state: tauri::State<BackendProcess>) -> Result<String, String
 
 #[tauri::command]
 async fn check_backend_health(state: tauri::State<'_, BackendProcess>) -> Result<String, String> {
-    // Check if the backend is actually alive
-    let mut child_guard = state.child.lock().map_err(|e| e.to_string())?;
-    let is_alive = match &mut *child_guard {
-        Some(child) => matches!(child.try_wait(), Ok(None)),
-        None => false,
+    // Check if the backend is actually alive (drop guard before await)
+    let is_alive = {
+        let mut child_guard = state.child.lock().map_err(|e| e.to_string())?;
+        match &mut *child_guard {
+            Some(child) => matches!(child.try_wait(), Ok(None)),
+            None => false,
+        }
     };
-    drop(child_guard);
 
     if !is_alive {
         return Ok("dead".to_string());
@@ -293,7 +294,7 @@ async fn check_backend_health(state: tauri::State<'_, BackendProcess>) -> Result
 
 #[tauri::command]
 fn save_window_state(
-    app: tauri::AppHandle,
+    _app: tauri::AppHandle,
     x: f64,
     y: f64,
     width: f64,
@@ -335,8 +336,9 @@ fn main() {
 
     // Resolve exe directory
     let exe_dir = std::env::current_exe()
+        .ok()
         .and_then(|p| p.parent().map(|p| p.to_path_buf()))
-        .unwrap_or_else(|_| PathBuf::from("."));
+        .unwrap_or_else(|| PathBuf::from("."));
     info!("Exe dir: {}", exe_dir.display());
 
     // Load config for window state
@@ -405,11 +407,6 @@ fn main() {
 
             // Wait for backend health check (non-blocking)
             let handle = app.handle().clone();
-            let state = app.state::<BackendProcess>();
-            let state_clone = state.inner().clone();
-            // We can't clone state, so we pass the child mutex guard idea
-            // Instead, we just do the initial health check inline
-
             tauri::async_runtime::spawn(async move {
                 match wait_for_backend().await {
                     Ok(()) => {
@@ -482,10 +479,10 @@ fn main() {
                 if let Ok(pos) = window.outer_position() {
                     if let Ok(size) = window.outer_size() {
                         let mut config = load_config();
-                        config.window_x = Some(pos.x);
-                        config.window_y = Some(pos.y);
-                        config.window_width = Some(size.width);
-                        config.window_height = Some(size.height);
+                        config.window_x = Some(pos.x as f64);
+                        config.window_y = Some(pos.y as f64);
+                        config.window_width = Some(size.width as f64);
+                        config.window_height = Some(size.height as f64);
                         save_config(&config);
                     }
                 }