Fix capture DSLR: pause avant capture + retry si I/O in progress

- Frontend: arrete le preview 300ms avant la capture
- Backend: 3 tentatives avec 500ms entre chaque si DSLR occupe

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend/camera.py

@@ -146,6 +146,7 @@ class Camera:
             return self._capture_simulation(chemin_dest)
 
     def _capture_gphoto2(self, chemin_dest: Path) -> Path | None:
+        for attempt in range(3):
             try:
                 chemin_camera = self.camera.capture(gp.GP_CAPTURE_IMAGE)
                 fichier_camera = gp.CameraFile()
@@ -156,6 +157,10 @@ class Camera:
                 log.info(f"Photo capturee (DSLR) : {chemin_dest}")
                 return chemin_dest
             except gp.GPhoto2Error as e:
+                if "I/O in progress" in str(e) and attempt < 2:
+                    log.warning(f"DSLR occupe, retry {attempt + 1}/3...")
+                    time.sleep(0.5)
+                    continue
                 log.error(f"Erreur capture DSLR : {e}")
                 return None
 

frontend/js/camera.js

@@ -46,9 +46,11 @@ async function lancerCapture() {
     }
 
     await compteARebours();
-    afficherFlash();
 
     arreterPreview();
+    await pause(300);  // Laisser le DSLR se liberer du preview
+
+    afficherFlash();
     const resultat = await apiPost('/api/capturer');
 
     if (resultat.erreur) {