fix: timing flash + couleur idle LED + diagnostic auto-brightness

backend/services/photobooth_service.py

@@ -191,26 +191,40 @@ class PhotoboothService:
         """Tente de recuperer une frame JPEG du liveview de photobooth-app.
 
         Essaie dans l'ordre :
-        1. /api/stream/snapshot — endpoint snapshot direct (si disponible)
-        2. /stream.mjpg — flux MJPEG classique, extrait la premiere frame
-        3. /api/stream — flux MJPEG alternatif
+        1. Endpoints snapshot direct (retour JPEG immédiat)
+        2. Flux MJPEG — extrait la premiere frame
 
         Retourne des bytes JPEG ou None si rien n'est disponible.
         """
-        # 1. Snapshot direct
-        for path in ("/api/stream/snapshot",):
+        # 1. Endpoints snapshot direct (differentes versions de photobooth-app)
+        snapshot_paths = (
+            "/api/stream/snapshot",
+            "/api/video/preview/snapshot",
+            "/api/livestream/snapshot",
+            "/api/cam/stream/snapshot",
+        )
+        for path in snapshot_paths:
             try:
                 async with httpx.AsyncClient(timeout=2.0) as client:
                     r = await client.get(f"{self._base}{path}")
                     if r.status_code == 200:
                         ct = r.headers.get("content-type", "")
                         if "jpeg" in ct or "image" in ct:
+                            logger.debug("Snapshot OK via %s", path)
                             return r.content
             except Exception as e:
                 logger.debug("Snapshot %s: %s", path, e)
 
-        # 2. Premiere frame d'un flux MJPEG
-        for path in ("/stream.mjpg", "/api/stream"):
+        # 2. Premiere frame d'un flux MJPEG (differentes versions)
+        mjpeg_paths = (
+            "/stream.mjpg",
+            "/api/stream",
+            "/api/video/stream",
+            "/api/video/preview",
+            "/api/livestream",
+            "/livestream",
+        )
+        for path in mjpeg_paths:
             try:
                 async with httpx.AsyncClient(timeout=3.0) as client:
                     async with client.stream("GET", f"{self._base}{path}") as resp:
@@ -223,12 +237,14 @@ class PhotoboothService:
                             if start >= 0:
                                 end = buf.find(b"\xff\xd9", start)
                                 if end >= 0:
+                                    logger.debug("MJPEG frame OK via %s", path)
                                     return buf[start:end + 2]
                             if len(buf) > 500_000:
                                 break
             except Exception as e:
                 logger.debug("MJPEG %s: %s", path, e)
 
+        logger.debug("Aucun endpoint liveview disponible sur %s", self._base)
         return None
 
     async def close(self):